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There are various things left to do: contrib dbsize and oid2name modules need work, and so does the documentation. Also someone should think about COMMENT ON TABLESPACE and maybe RENAME TABLESPACE. Also initlocation is dead, it just doesn't know it yet. Gavin Sherry and Tom Lane.
4642 lines
150 KiB
Plaintext
4642 lines
150 KiB
Plaintext
<!--
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Documentation of the system catalogs, directed toward PostgreSQL developers
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$PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.88 2004/06/18 06:13:02 tgl Exp $
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-->
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<chapter id="catalogs">
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<title>System Catalogs</title>
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<para>
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The system catalogs are the place where a relational database
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management system stores schema metadata, such as information about
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tables and columns, and internal bookkeeping information.
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<productname>PostgreSQL</productname>'s system catalogs are regular
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tables. You can drop and recreate the tables, add columns, insert
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and update values, and severely mess up your system that way.
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Normally, one should not change the system catalogs by hand, there
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are always SQL commands to do that. (For example, <command>CREATE
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DATABASE</command> inserts a row into the
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<structname>pg_database</structname> catalog --- and actually
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creates the database on disk.) There are some exceptions for
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particularly esoteric operations, such as adding index access methods.
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</para>
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<sect1 id="catalogs-overview">
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<title>Overview</title>
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<para>
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<xref linkend="catalog-table"> lists the system catalogs.
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More detailed documentation of each catalog follows below.
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</para>
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<para>
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Most system catalogs are copied from the template database during
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database creation and are thereafter database-specific. A few
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catalogs are physically shared across all databases in a cluster;
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these are marked in the descriptions of the individual catalogs.
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</para>
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<table id="catalog-table">
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<title>System Catalogs</title>
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<tgroup cols="2">
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<thead>
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<row>
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<entry>Catalog Name</entry>
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<entry>Purpose</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry><link linkend="catalog-pg-aggregate"><structname>pg_aggregate</structname></link></entry>
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<entry>aggregate functions</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-am"><structname>pg_am</structname></link></entry>
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<entry>index access methods</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-amop"><structname>pg_amop</structname></link></entry>
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<entry>access method operators</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-amproc"><structname>pg_amproc</structname></link></entry>
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<entry>access method support procedures</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-attrdef"><structname>pg_attrdef</structname></link></entry>
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<entry>column default values</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-attribute"><structname>pg_attribute</structname></link></entry>
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<entry>table columns (<quote>attributes</quote>)</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-cast"><structname>pg_cast</structname></link></entry>
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<entry>casts (data type conversions)</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-class"><structname>pg_class</structname></link></entry>
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<entry>tables, indexes, sequences (<quote>relations</quote>)</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-constraint"><structname>pg_constraint</structname></link></entry>
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<entry>check constraints, unique constraints, primary key constraints, foreign key constraints</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-conversion"><structname>pg_conversion</structname></link></entry>
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<entry>encoding conversion information</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-database"><structname>pg_database</structname></link></entry>
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<entry>databases within this database cluster</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-depend"><structname>pg_depend</structname></link></entry>
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<entry>dependencies between database objects</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-description"><structname>pg_description</structname></link></entry>
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<entry>descriptions or comments on database objects</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-group"><structname>pg_group</structname></link></entry>
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<entry>groups of database users</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-index"><structname>pg_index</structname></link></entry>
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<entry>additional index information</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-inherits"><structname>pg_inherits</structname></link></entry>
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<entry>table inheritance hierarchy</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-language"><structname>pg_language</structname></link></entry>
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<entry>languages for writing functions</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-largeobject"><structname>pg_largeobject</structname></link></entry>
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<entry>large objects</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-listener"><structname>pg_listener</structname></link></entry>
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<entry>asynchronous notification support</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-namespace"><structname>pg_namespace</structname></link></entry>
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<entry>schemas</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-opclass"><structname>pg_opclass</structname></link></entry>
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<entry>index access method operator classes</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-operator"><structname>pg_operator</structname></link></entry>
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<entry>operators</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link></entry>
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<entry>functions and procedures</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-rewrite"><structname>pg_rewrite</structname></link></entry>
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<entry>query rewrite rules</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-shadow"><structname>pg_shadow</structname></link></entry>
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<entry>database users</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-statistic"><structname>pg_statistic</structname></link></entry>
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<entry>planner statistics</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-tablespace"><structname>pg_tablespace</structname></link></entry>
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<entry>tablespaces within this database cluster</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-trigger"><structname>pg_trigger</structname></link></entry>
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<entry>triggers</entry>
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</row>
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<row>
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<entry><link linkend="catalog-pg-type"><structname>pg_type</structname></link></entry>
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<entry>data types</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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</sect1>
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<sect1 id="catalog-pg-aggregate">
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<title><structname>pg_aggregate</structname></title>
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<indexterm zone="catalog-pg-aggregate">
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<primary>pg_aggregate</primary>
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</indexterm>
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<para>
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The catalog <structname>pg_aggregate</structname> stores information about
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aggregate functions. An aggregate function is a function that
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operates on a set of values (typically one column from each row
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that matches a query condition) and returns a single value computed
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from all these values. Typical aggregate functions are
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<function>sum</function>, <function>count</function>, and
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<function>max</function>. Each entry in
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<structname>pg_aggregate</structname> is an extension of an entry
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in <structname>pg_proc</structname>. The <structname>pg_proc</structname>
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entry carries the aggregate's name, input and output data types, and
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other information that is similar to ordinary functions.
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</para>
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<table>
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<title><structname>pg_aggregate</> Columns</title>
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<tgroup cols=4>
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<thead>
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<row>
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<entry>Name</entry>
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<entry>Type</entry>
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<entry>References</entry>
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<entry>Description</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry><structfield>aggfnoid</structfield></entry>
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<entry><type>regproc</type></entry>
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<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
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<entry><structname>pg_proc</structname> OID of the aggregate function</entry>
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</row>
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<row>
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<entry><structfield>aggtransfn</structfield></entry>
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<entry><type>regproc</type></entry>
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<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
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<entry>Transition function</entry>
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</row>
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<row>
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<entry><structfield>aggfinalfn</structfield></entry>
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<entry><type>regproc</type></entry>
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<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
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<entry>Final function (zero if none)</entry>
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</row>
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<row>
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<entry><structfield>aggtranstype</structfield></entry>
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<entry><type>oid</type></entry>
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<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
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<entry>The type of the aggregate function's internal transition (state) data</entry>
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</row>
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<row>
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<entry><structfield>agginitval</structfield></entry>
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<entry><type>text</type></entry>
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<entry></entry>
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<entry>
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The initial value of the transition state. This is a text
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field containing the initial value in its external string
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representation. If the value is null, the transition state
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value starts out null.
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</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<para>
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New aggregate functions are registered with the <command>CREATE
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AGGREGATE</command> command. See <xref linkend="xaggr"> for more
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information about writing aggregate functions and the meaning of
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the transition functions, etc.
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</para>
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</sect1>
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<sect1 id="catalog-pg-am">
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<title><structname>pg_am</structname></title>
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<indexterm zone="catalog-pg-am">
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<primary>pg_am</primary>
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</indexterm>
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<para>
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The catalog <structname>pg_am</structname> stores information about index access
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methods. There is one row for each index access method supported by
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the system.
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</para>
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<table>
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<title><structname>pg_am</> Columns</title>
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<tgroup cols=4>
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<thead>
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<row>
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<entry>Name</entry>
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<entry>Type</entry>
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<entry>References</entry>
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<entry>Description</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry><structfield>amname</structfield></entry>
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<entry><type>name</type></entry>
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<entry></entry>
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<entry>Name of the access method</entry>
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</row>
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<row>
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<entry><structfield>amowner</structfield></entry>
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<entry><type>int4</type></entry>
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<entry><literal><link linkend="catalog-pg-shadow"><structname>pg_shadow</structname></link>.usesysid</literal></entry>
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<entry>User ID of the owner (currently not used)</entry>
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</row>
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<row>
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<entry><structfield>amstrategies</structfield></entry>
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<entry><type>int2</type></entry>
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<entry></entry>
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<entry>Number of operator strategies for this access method</entry>
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</row>
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<row>
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<entry><structfield>amsupport</structfield></entry>
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<entry><type>int2</type></entry>
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<entry></entry>
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<entry>Number of support routines for this access method</entry>
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</row>
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<row>
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<entry><structfield>amorderstrategy</structfield></entry>
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<entry><type>int2</type></entry>
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<entry></entry>
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<entry>Zero if the index offers no sort order, otherwise the strategy
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number of the strategy operator that describes the sort order</entry>
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</row>
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<row>
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<entry><structfield>amcanunique</structfield></entry>
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<entry><type>bool</type></entry>
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<entry></entry>
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<entry>Does the access method support unique indexes?</entry>
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</row>
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<row>
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<entry><structfield>amcanmulticol</structfield></entry>
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<entry><type>bool</type></entry>
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<entry></entry>
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<entry>Does the access method support multicolumn indexes?</entry>
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</row>
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<row>
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<entry><structfield>amindexnulls</structfield></entry>
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<entry><type>bool</type></entry>
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<entry></entry>
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<entry>Does the access method support null index entries?</entry>
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</row>
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<row>
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<entry><structfield>amconcurrent</structfield></entry>
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<entry><type>bool</type></entry>
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<entry></entry>
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<entry>Does the access method support concurrent updates?</entry>
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</row>
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<row>
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<entry><structfield>amgettuple</structfield></entry>
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<entry><type>regproc</type></entry>
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<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
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<entry><quote>Next valid tuple</quote> function</entry>
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</row>
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<row>
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<entry><structfield>aminsert</structfield></entry>
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<entry><type>regproc</type></entry>
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<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
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<entry><quote>Insert this tuple</quote> function</entry>
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</row>
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<row>
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<entry><structfield>ambeginscan</structfield></entry>
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<entry><type>regproc</type></entry>
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<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
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<entry><quote>Start new scan</quote> function</entry>
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</row>
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<row>
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<entry><structfield>amrescan</structfield></entry>
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<entry><type>regproc</type></entry>
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<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
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<entry><quote>Restart this scan</quote> function</entry>
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</row>
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<row>
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<entry><structfield>amendscan</structfield></entry>
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<entry><type>regproc</type></entry>
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<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
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<entry><quote>End this scan</quote> function</entry>
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</row>
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<row>
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<entry><structfield>ammarkpos</structfield></entry>
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<entry><type>regproc</type></entry>
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<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
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<entry><quote>Mark current scan position</quote> function</entry>
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</row>
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<row>
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<entry><structfield>amrestrpos</structfield></entry>
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<entry><type>regproc</type></entry>
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<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
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<entry><quote>Restore marked scan position</quote> function</entry>
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</row>
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<row>
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<entry><structfield>ambuild</structfield></entry>
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<entry><type>regproc</type></entry>
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<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
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<entry><quote>Build new index</quote> function</entry>
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</row>
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<row>
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<entry><structfield>ambulkdelete</structfield></entry>
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<entry><type>regproc</type></entry>
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<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
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<entry>Bulk-delete function</entry>
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</row>
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<row>
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<entry><structfield>amvacuumcleanup</structfield></entry>
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<entry><type>regproc</type></entry>
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<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
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<entry>Post-<command>VACUUM</command> cleanup function</entry>
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</row>
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<row>
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|
<entry><structfield>amcostestimate</structfield></entry>
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<entry><type>regproc</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
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|
<entry>Function to estimate cost of an index scan</entry>
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|
</row>
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|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
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|
An index access method that supports multiple columns (has
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<structfield>amcanmulticol</structfield> true) <emphasis>must</>
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|
support indexing null values in columns after the first, because the planner
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|
will assume the index can be used for queries on just the first
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column(s). For example, consider an index on (a,b) and a query with
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<literal>WHERE a = 4</literal>. The system will assume the index can be used to scan for
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rows with <literal>a = 4</literal>, which is wrong if the index omits rows where <literal>b</> is null.
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|
It is, however, OK to omit rows where the first indexed column is null.
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|
(GiST currently does so.)
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|
<structfield>amindexnulls</structfield> should be set true only if the
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|
index access method indexes all rows, including arbitrary combinations of null values.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-amop">
|
|
<title><structname>pg_amop</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-amop">
|
|
<primary>pg_amop</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_amop</structname> stores information about operators
|
|
associated with index access method operator classes. There is one
|
|
row for each operator that is a member of an operator class.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_amop</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
|
|
<row>
|
|
<entry><structfield>amopclaid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-opclass"><structname>pg_opclass</structname></link>.oid</literal></entry>
|
|
<entry>The index operator class this entry is for</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>amopsubtype</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
|
|
<entry>Subtype to distinguish multiple entries for one strategy;
|
|
zero for default</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>amopstrategy</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>Operator strategy number</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>amopreqcheck</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>Index hit must be rechecked</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>amopopr</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-operator"><structname>pg_operator</structname></link>.oid</literal></entry>
|
|
<entry>OID of the operator</entry>
|
|
</row>
|
|
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-amproc">
|
|
<title><structname>pg_amproc</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-amproc">
|
|
<primary>pg_amproc</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_amproc</structname> stores information about support
|
|
procedures
|
|
associated with index access method operator classes. There is one
|
|
row for each support procedure belonging to an operator class.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_amproc</structname> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
|
|
<row>
|
|
<entry><structfield>amopclaid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-opclass"><structname>pg_opclass</structname></link>.oid</literal></entry>
|
|
<entry>The index operator class this entry is for</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>amprocsubtype</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
|
|
<entry>Subtype, if cross-type routine, else zero</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>amprocnum</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>Support procedure number</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>amproc</structfield></entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
|
|
<entry>OID of the procedure</entry>
|
|
</row>
|
|
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-attrdef">
|
|
<title><structname>pg_attrdef</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-attrdef">
|
|
<primary>pg_attrdef</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_attrdef</structname> stores column default values. The main information
|
|
about columns is stored in <structname>pg_attribute</structname>
|
|
(see below). Only columns that explicitly specify a default value
|
|
(when the table is created or the column is added) will have an
|
|
entry here.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_attrdef</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>adrelid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>The table this column belongs to</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>adnum</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-attribute"><structname>pg_attribute</structname></link>.attnum</literal></entry>
|
|
<entry>The number of the column</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>adbin</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>The internal representation of the column default value</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>adsrc</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>A human-readable representation of the default value</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-attribute">
|
|
<title><structname>pg_attribute</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-attribute">
|
|
<primary>pg_attribute</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_attribute</structname> stores information about
|
|
table columns. There will be exactly one
|
|
<structname>pg_attribute</structname> row for every column in every
|
|
table in the database. (There will also be attribute entries for
|
|
indexes and other objects. See <structname>pg_class</structname>.)
|
|
</para>
|
|
|
|
<para>
|
|
The term attribute is equivalent to column and is used for
|
|
historical reasons.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_attribute</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>attrelid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>The table this column belongs to</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>attname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>The column name</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>atttypid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
|
|
<entry>The data type of this column</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>attstattarget</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
<structfield>attstattarget</structfield> controls the level of detail
|
|
of statistics accumulated for this column by
|
|
<command>ANALYZE</command>.
|
|
A zero value indicates that no statistics should be collected.
|
|
A negative value says to use the system default statistics target.
|
|
The exact meaning of positive values is data type-dependent.
|
|
For scalar data types, <structfield>attstattarget</structfield>
|
|
is both the target number of <quote>most common values</quote>
|
|
to collect, and the target number of histogram bins to create.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>attlen</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
A copy of <literal>pg_type.typlen</literal> of this column's
|
|
type
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>attnum</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
The number of the column. Ordinary columns are numbered from 1
|
|
up. System columns, such as <structfield>oid</structfield>,
|
|
have (arbitrary) negative numbers.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>attndims</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Number of dimensions, if the column is an array type; otherwise 0.
|
|
(Presently, the number of dimensions of an array is not enforced,
|
|
so any nonzero value effectively means <quote>it's an array</>.)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>attcacheoff</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Always -1 in storage, but when loaded into a row descriptor
|
|
in memory this may be updated to cache the offset of the attribute
|
|
within the row.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>atttypmod</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
<structfield>atttypmod</structfield> records type-specific data
|
|
supplied at table creation time (for example, the maximum
|
|
length of a <type>varchar</type> column). It is passed to
|
|
type-specific input functions and length coercion functions.
|
|
The value will generally be -1 for types that do not need <structfield>atttypmod</>.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>attbyval</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
A copy of <literal>pg_type.typbyval</> of this column's type
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>attstorage</structfield></entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Normally a copy of <literal>pg_type.typstorage</> of this
|
|
column's type. For TOAST-able data types, this can be altered
|
|
after column creation to control storage policy.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>attalign</structfield></entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
A copy of <literal>pg_type.typalign</> of this column's type
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>attnotnull</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
This represents a not-null constraint. It is possible to
|
|
change this column to enable or disable the constraint.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>atthasdef</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
This column has a default value, in which case there will be a
|
|
corresponding entry in the <structname>pg_attrdef</structname>
|
|
catalog that actually defines the value.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>attisdropped</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
This column has been dropped and is no longer valid. A dropped
|
|
column is still physically present in the table, but is
|
|
ignored by the parser and so cannot be accessed via SQL.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>attislocal</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
This column is defined locally in the relation. Note that a column may
|
|
be locally defined and inherited simultaneously.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>attinhcount</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
The number of direct ancestors this column has. A column with a
|
|
nonzero number of ancestors cannot be dropped nor renamed.
|
|
</entry>
|
|
</row>
|
|
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-cast">
|
|
<title><structname>pg_cast</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-cast">
|
|
<primary>pg_cast</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_cast</structname> stores data type conversion paths,
|
|
both built-in paths and those defined with <command>CREATE CAST</command>.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structfield>pg_cast</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>castsource</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
|
|
<entry>OID of the source data type</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>casttarget</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
|
|
<entry>OID of the target data type</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>castfunc</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
The OID of the function to use to perform this cast. Zero is
|
|
stored if the data types are binary compatible (that is, no
|
|
run-time operation is needed to perform the cast).
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>castcontext</structfield></entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Indicates what contexts the cast may be invoked in.
|
|
<literal>e</> means only as an explicit cast (using
|
|
<literal>CAST</> or <literal>::</> syntax).
|
|
<literal>a</> means implicitly in assignment
|
|
to a target column, as well as explicitly.
|
|
<literal>i</> means implicitly in expressions, as well as the
|
|
other cases.
|
|
</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
The cast functions listed in <structname>pg_cast</structname> must
|
|
always take the cast source type as their first argument type, and
|
|
return the cast destination type as their result type. A cast
|
|
function can have up to three arguments. The second argument,
|
|
if present, must be type <type>integer</>; it receives the type
|
|
modifier associated with the destination type, or <literal>-1</>
|
|
if there is none. The third argument,
|
|
if present, must be type <type>boolean</>; it receives <literal>true</>
|
|
if the cast is an explicit cast, <literal>false</> otherwise.
|
|
</para>
|
|
|
|
<para>
|
|
It is legitimate to create a <structname>pg_cast</structname> entry
|
|
in which the source and target types are the same, if the associated
|
|
function takes more than one argument. Such entries represent
|
|
<quote>length coercion functions</> that coerce values of the type
|
|
to be legal for a particular type modifier value. Note however that
|
|
at present there is no support for associating non-default type
|
|
modifiers with user-created data types, and so this facility is only
|
|
of use for the small number of built-in types that have type modifier
|
|
syntax built into the grammar.
|
|
</para>
|
|
|
|
<para>
|
|
When a <structname>pg_cast</structname> entry has different source and
|
|
target types and a function that takes more than one argument, it
|
|
represents converting from one type to another and applying a length
|
|
coercion in a single step. When no such entry is available, coercion
|
|
to a type that uses a type modifier involves two steps, one to
|
|
convert between datatypes and a second to apply the modifier.
|
|
</para>
|
|
</sect1>
|
|
|
|
<sect1 id="catalog-pg-class">
|
|
<title><structname>pg_class</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-class">
|
|
<primary>pg_class</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_class</structname> catalogs tables and most
|
|
everything else that has columns or is otherwise similar to a
|
|
table. This includes indexes (but see also
|
|
<structname>pg_index</structname>), sequences, views, composite types,
|
|
and some kinds of special relation; see <structfield>relkind</>.
|
|
Below, when we mean all of these
|
|
kinds of objects we speak of <quote>relations</quote>. Not all
|
|
columns are meaningful for all relation types.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_class</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>relname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Name of the table, index, view, etc.</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relnamespace</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-namespace"><structname>pg_namespace</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
The OID of the namespace that contains this relation
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>reltype</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
The OID of the data type that corresponds to this table's rowtype,
|
|
if any (zero for indexes, which have no <structname>pg_type</> entry)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relowner</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-shadow"><structname>pg_shadow</structname></link>.usesysid</literal></entry>
|
|
<entry>Owner of the relation</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relam</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-am"><structname>pg_am</structname></link>.oid</literal></entry>
|
|
<entry>If this is an index, the access method used (B-tree, hash, etc.)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relfilenode</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry></entry>
|
|
<entry>Name of the on-disk file of this relation; 0 if none</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>reltablespace</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-tablespace"><structname>pg_tablespace</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
The tablespace in which this relation is stored. If zero,
|
|
the database's default tablespace is implied. (Not meaningful
|
|
if the relation has no on-disk file.)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relpages</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Size of the on-disk representation of this table in pages (size
|
|
<symbol>BLCKSZ</symbol>).
|
|
This is only an estimate used by the planner.
|
|
It is updated by <command>VACUUM</command>,
|
|
<command>ANALYZE</command>, and <command>CREATE INDEX</command>.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>reltuples</structfield></entry>
|
|
<entry><type>float4</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Number of rows in the table.
|
|
This is only an estimate used by the planner.
|
|
It is updated by <command>VACUUM</command>,
|
|
<command>ANALYZE</command>, and <command>CREATE INDEX</command>.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>reltoastrelid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
OID of the TOAST table associated with this table, 0 if none.
|
|
The TOAST table stores large attributes <quote>out of
|
|
line</quote> in a secondary table.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>reltoastidxid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
For a TOAST table, the OID of its index. 0 if not a TOAST table.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relhasindex</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
True if this is a table and it has (or recently had) any
|
|
indexes. This is set by <command>CREATE INDEX</command>, but
|
|
not cleared immediately by <command>DROP INDEX</command>.
|
|
<command>VACUUM</command> clears <structfield>relhasindex</> if it finds the
|
|
table has no indexes.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relisshared</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>True if this table is shared across all databases in the
|
|
cluster. Only certain system catalogs (such as
|
|
<structname>pg_database</structname>) are shared.</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relkind</structfield></entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
<literal>r</> = ordinary table, <literal>i</> = index,
|
|
<literal>S</> = sequence, <literal>v</> = view, <literal>c</> =
|
|
composite type, <literal>s</> = special, <literal>t</> = TOAST
|
|
table
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relnatts</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Number of user columns in the relation (system columns not
|
|
counted). There must be this many corresponding entries in
|
|
<structname>pg_attribute</structname>. See also
|
|
<literal>pg_attribute.attnum</literal>.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relchecks</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Number of check constraints on the table; see
|
|
<structname>pg_constraint</structname> catalog
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>reltriggers</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Number of triggers on the table; see
|
|
<structname>pg_trigger</structname> catalog
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relukeys</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>unused (<emphasis>not</emphasis> the number of unique keys)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relfkeys</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>unused (<emphasis>not</emphasis> the number of foreign keys on the table)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relrefs</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>unused</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relhasoids</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
True if we generate an OID for each row of the relation.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relhaspkey</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
True if the table has (or once had) a primary key.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relhasrules</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>Table has rules; see
|
|
<structname>pg_rewrite</structname> catalog
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relhassubclass</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>At least one table inherits from this one</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>relacl</structfield></entry>
|
|
<entry><type>aclitem[]</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Access privileges; see the descriptions of
|
|
<command>GRANT</command> and <command>REVOKE</command> for
|
|
details.
|
|
</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
</sect1>
|
|
|
|
<sect1 id="catalog-pg-constraint">
|
|
<title><structname>pg_constraint</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-constraint">
|
|
<primary>pg_constraint</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_constraint</structname> stores check, primary key, unique, and foreign
|
|
key constraints on tables. (Column constraints are not treated
|
|
specially. Every column constraint is equivalent to some table
|
|
constraint.) Not-null constraints are represented in the
|
|
<structname>pg_attribute</> catalog.
|
|
</para>
|
|
|
|
<para>
|
|
Check constraints on domains are stored here, too.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_constraint</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>conname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Constraint name (not necessarily unique!)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>connamespace</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-namespace"><structname>pg_namespace</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
The OID of the namespace that contains this constraint
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>contype</structfield></entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
<literal>c</> = check constraint,
|
|
<literal>f</> = foreign key constraint,
|
|
<literal>p</> = primary key constraint,
|
|
<literal>u</> = unique constraint
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>condeferrable</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>Is the constraint deferrable?</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>condeferred</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>Is the constraint deferred by default?</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>conrelid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>The table this constraint is on; 0 if not a table constraint</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>contypid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
|
|
<entry>The domain this constraint is on; 0 if not a domain constraint</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>confrelid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>If a foreign key, the referenced table; else 0</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>confupdtype</structfield></entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>Foreign key update action code</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>confdeltype</structfield></entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>Foreign key deletion action code</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>confmatchtype</structfield></entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>Foreign key match type</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>conkey</structfield></entry>
|
|
<entry><type>int2[]</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-attribute"><structname>pg_attribute</structname></link>.attnum</></entry>
|
|
<entry>If a table constraint, list of columns which the constraint constrains</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>confkey</structfield></entry>
|
|
<entry><type>int2[]</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-attribute"><structname>pg_attribute</structname></link>.attnum</></entry>
|
|
<entry>If a foreign key, list of the referenced columns</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>conbin</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>If a check constraint, an internal representation of the expression</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>consrc</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>If a check constraint, a human-readable representation of the expression</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<note>
|
|
<para>
|
|
<structfield>consrc</structfield> is not updated when referenced objects
|
|
change; for example, it won't track renaming of columns. Rather than
|
|
relying on this field, it's best to use <function>pg_get_constraintdef()</>
|
|
to extract the definition of a check constraint.
|
|
</para>
|
|
</note>
|
|
|
|
<note>
|
|
<para>
|
|
<literal>pg_class.relchecks</literal> needs to agree with the
|
|
number of check-constraint entries found in this table for the
|
|
given relation.
|
|
</para>
|
|
</note>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="catalog-pg-conversion">
|
|
<title><structname>pg_conversion</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-conversion">
|
|
<primary>pg_conversion</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_conversion</structname> stores encoding conversion information. See
|
|
<command>CREATE CONVERSION</command> for more information.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_conversion</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>conname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Conversion name (unique within a namespace)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>connamespace</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-namespace"><structname>pg_namespace</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
The OID of the namespace that contains this conversion
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>conowner</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-shadow"><structname>pg_shadow</structname></link>.usesysid</literal></entry>
|
|
<entry>Owner of the conversion</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>conforencoding</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>Source encoding ID</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>contoencoding</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>Destination encoding ID</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>conproc</structfield></entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
|
|
<entry>Conversion procedure</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>condefault</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>True if this is the default conversion</entry>
|
|
</row>
|
|
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="catalog-pg-database">
|
|
<title><structname>pg_database</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-database">
|
|
<primary>pg_database</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_database</structname> stores information
|
|
about the available databases. Databases are created with the
|
|
<command>CREATE DATABASE</command> command. Consult
|
|
<xref linkend="managing-databases"> for details about the meaning of some of the
|
|
parameters.
|
|
</para>
|
|
|
|
<para>
|
|
Unlike most system catalogs, <structname>pg_database</structname>
|
|
is shared across all databases of a cluster: there is only one
|
|
copy of <structname>pg_database</structname> per cluster, not
|
|
one per database.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_database</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>datname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Database name</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>datdba</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-shadow"><structname>pg_shadow</structname></link>.usesysid</literal></entry>
|
|
<entry>Owner of the database, usually the user who created it</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>encoding</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>Character encoding for this database</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>datistemplate</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
If true then this database can be used in the
|
|
<literal>TEMPLATE</literal> clause of <command>CREATE
|
|
DATABASE</command> to create a new database as a clone of
|
|
this one.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>datallowconn</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
If false then no one can connect to this database. This is
|
|
used to protect the <literal>template0</> database from being altered.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>datlastsysoid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Last system OID in the database; useful
|
|
particularly to <application>pg_dump</application>
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>datvacuumxid</structfield></entry>
|
|
<entry><type>xid</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
All rows inserted or deleted by transaction IDs before this one
|
|
have been marked as known committed or known aborted in this database.
|
|
This is used to determine when commit-log space can be recycled.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>datfrozenxid</structfield></entry>
|
|
<entry><type>xid</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
All rows inserted by transaction IDs before this one have been
|
|
relabeled with a permanent (<quote>frozen</>) transaction ID in this
|
|
database. This is useful to check whether a database must be vacuumed
|
|
soon to avoid transaction ID wrap-around problems.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>dattablespace</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-tablespace"><structname>pg_tablespace</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
The default tablespace for the database.
|
|
Within this database, all tables for which
|
|
<structname>pg_class</>.<structfield>reltablespace</> is zero
|
|
will be stored in this tablespace; in particular, all the non-shared
|
|
system catalogs will be there.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>datconfig</structfield></entry>
|
|
<entry><type>text[]</type></entry>
|
|
<entry></entry>
|
|
<entry>Session defaults for run-time configuration variables</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>datacl</structfield></entry>
|
|
<entry><type>aclitem[]</type></entry>
|
|
<entry></entry>
|
|
<entry>Access privileges</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-depend">
|
|
<title><structname>pg_depend</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-depend">
|
|
<primary>pg_depend</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_depend</structname> records the dependency
|
|
relationships between database objects. This information allows
|
|
<command>DROP</> commands to find which other objects must be dropped
|
|
by <command>DROP CASCADE</> or prevent dropping in the <command>DROP
|
|
RESTRICT</> case.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_depend</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>classid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>The OID of the system catalog the dependent object is in</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>objid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>any OID column</entry>
|
|
<entry>The OID of the specific dependent object</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>objsubid</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
For a table column, this is the column number (the
|
|
<structfield>objid</> and <structfield>classid</> refer to the
|
|
table itself). For all other object types, this column is
|
|
zero.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>refclassid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>The OID of the system catalog the referenced object is in</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>refobjid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>any OID column</entry>
|
|
<entry>The OID of the specific referenced object</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>refobjsubid</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
For a table column, this is the column number (the
|
|
<structfield>refobjid</> and <structfield>refclassid</> refer
|
|
to the table itself). For all other object types, this column
|
|
is zero.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>deptype</structfield></entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
A code defining the specific semantics of this dependency relationship; see text.
|
|
</entry>
|
|
</row>
|
|
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
In all cases, a <structname>pg_depend</structname> entry indicates that the
|
|
referenced object may not be dropped without also dropping the dependent
|
|
object. However, there are several subflavors identified by
|
|
<structfield>deptype</>:
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><symbol>DEPENDENCY_NORMAL</> (<literal>n</>)</term>
|
|
<listitem>
|
|
<para>
|
|
A normal relationship between separately-created objects. The
|
|
dependent object may be dropped without affecting the
|
|
referenced object. The referenced object may only be dropped
|
|
by specifying <literal>CASCADE</>, in which case the dependent
|
|
object is dropped, too. Example: a table column has a normal
|
|
dependency on its data type.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><symbol>DEPENDENCY_AUTO</> (<literal>a</>)</term>
|
|
<listitem>
|
|
<para>
|
|
The dependent object can be dropped separately from the
|
|
referenced object, and should be automatically dropped
|
|
(regardless of <literal>RESTRICT</> or <literal>CASCADE</>
|
|
mode) if the referenced object is dropped. Example: a named
|
|
constraint on a table is made autodependent on the table, so
|
|
that it will go away if the table is dropped.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><symbol>DEPENDENCY_INTERNAL</> (<literal>i</>)</term>
|
|
<listitem>
|
|
<para>
|
|
The dependent object was created as part of creation of the
|
|
referenced object, and is really just a part of its internal
|
|
implementation. A <command>DROP</> of the dependent object
|
|
will be disallowed outright (we'll tell the user to issue a
|
|
<command>DROP</> against the referenced object, instead). A
|
|
<command>DROP</> of the referenced object will be propagated
|
|
through to drop the dependent object whether
|
|
<command>CASCADE</> is specified or not. Example: a trigger
|
|
that's created to enforce a foreign-key constraint is made
|
|
internally dependent on the constraint's
|
|
<structname>pg_constraint</> entry.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><symbol>DEPENDENCY_PIN</> (<literal>p</>)</term>
|
|
<listitem>
|
|
<para>
|
|
There is no dependent object; this type of entry is a signal
|
|
that the system itself depends on the referenced object, and so
|
|
that object must never be deleted. Entries of this type are
|
|
created only by <command>initdb</command>. The columns for the
|
|
dependent object contain zeroes.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
|
|
Other dependency flavors may be needed in future.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-description">
|
|
<title><structname>pg_description</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-description">
|
|
<primary>pg_description</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_description</> can store an optional description or
|
|
comment for each database object. Descriptions can be manipulated
|
|
with the <command>COMMENT</command> command and viewed with
|
|
<application>psql</application>'s <literal>\d</literal> commands.
|
|
Descriptions of many built-in system objects are provided in the initial
|
|
contents of <structname>pg_description</structname>.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_description</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>objoid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>any OID column</entry>
|
|
<entry>The OID of the object this description pertains to</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>classoid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>The OID of the system catalog this object appears in</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>objsubid</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
For a comment on a table column, this is the column number (the
|
|
<structfield>objoid</> and <structfield>classoid</> refer to
|
|
the table itself). For all other object types, this column is
|
|
zero.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>description</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>Arbitrary text that serves as the description of this object.</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-group">
|
|
<title><structname>pg_group</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-group">
|
|
<primary>pg_group</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_group</structname> defines groups and stores what users belong to what
|
|
groups. Groups are created with the <command>CREATE
|
|
GROUP</command> command. Consult <xref linkend="user-manag"> for information
|
|
about user privilege management.
|
|
</para>
|
|
|
|
<para>
|
|
Because user and group identities are cluster-wide,
|
|
<structname>pg_group</structname>
|
|
is shared across all databases of a cluster: there is only one
|
|
copy of <structname>pg_group</structname> per cluster, not
|
|
one per database.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_group</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>groname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Name of the group</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>grosysid</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>An arbitrary number to identify this group</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>grolist</structfield></entry>
|
|
<entry><type>int4[]</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-shadow"><structname>pg_shadow</structname></link>.usesysid</literal></entry>
|
|
<entry>An array containing the IDs of the users in this group</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-index">
|
|
<title><structname>pg_index</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-index">
|
|
<primary>pg_index</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_index</structname> contains part of the information
|
|
about indexes. The rest is mostly in
|
|
<structname>pg_class</structname>.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_index</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>indexrelid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>The OID of the <structname>pg_class</> entry for this index</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>indrelid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>The OID of the <structname>pg_class</> entry for the table this index is for</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>indkey</structfield></entry>
|
|
<entry><type>int2vector</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-attribute"><structname>pg_attribute</structname></link>.attnum</literal></entry>
|
|
<entry>
|
|
This is an array of <structfield>indnatts</structfield> (up to
|
|
<symbol>INDEX_MAX_KEYS</symbol>) values that indicate which
|
|
table columns this index indexes. For example a value of
|
|
<literal>1 3</literal> would mean that the first and the third table
|
|
columns make up the index key. A zero in this array indicates that the
|
|
corresponding index attribute is an expression over the table columns,
|
|
rather than a simple column reference.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>indclass</structfield></entry>
|
|
<entry><type>oidvector</type></entry>
|
|
<entry><link linkend="catalog-pg-opclass"><structname>pg_opclass</structname></link>.oid</entry>
|
|
<entry>
|
|
For each column in the index key this contains the OID of
|
|
the operator class to use. See
|
|
<structname>pg_opclass</structname> for details.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>indnatts</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>The number of columns in the index (duplicates
|
|
<literal>pg_class.relnatts</literal>)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>indisunique</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>If true, this is a unique index.</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>indisprimary</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>If true, this index represents the primary key of the table.
|
|
(<structfield>indisunique</> should always be true when this is true.)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>indisclustered</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>If true, the table was last clustered on this index.</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>indexprs</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>Expression trees (in <function>nodeToString()</function> representation)
|
|
for index attributes that are not simple column references. This is a
|
|
list with one element for each zero entry in <structfield>indkey</>.
|
|
Null if all index attributes are simple references.</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>indpred</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>Expression tree (in <function>nodeToString()</function> representation)
|
|
for partial index predicate. Null if not a partial index.</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-inherits">
|
|
<title><structname>pg_inherits</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-inherits">
|
|
<primary>pg_inherits</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_inherits</> records information about
|
|
table inheritance hierarchies.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_inherits</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>inhrelid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
The OID of the child table.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>inhparent</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
The OID of the parent table.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>inhseqno</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
If there is more than one parent for a child table (multiple
|
|
inheritance), this number tells the order in which the
|
|
inherited columns are to be arranged. The count starts at 1.
|
|
</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-language">
|
|
<title><structname>pg_language</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-language">
|
|
<primary>pg_language</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_language</structname> registers call interfaces or
|
|
languages in which you can write functions or stored procedures.
|
|
See under <command>CREATE LANGUAGE</command> and in
|
|
<xref linkend="xplang"> for more information about language handlers.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_language</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>lanname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Name of the language (to be specified when creating a function)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>lanispl</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
This is false for internal languages (such as
|
|
<acronym>SQL</acronym>) and true for user-defined languages.
|
|
Currently, <application>pg_dump</application> still uses this
|
|
to determine which languages need to be dumped, but this may be
|
|
replaced by a different mechanism sometime.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>lanpltrusted</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
This is a trusted language. See under <command>CREATE
|
|
LANGUAGE</command> what this means. If this is an internal
|
|
language (<structfield>lanispl</structfield> is false) then
|
|
this column is meaningless.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>lanplcallfoid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
For noninternal languages this references the language
|
|
handler, which is a special function that is responsible for
|
|
executing all functions that are written in the particular
|
|
language.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>lanvalidator</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
This references a language validator function that is responsible
|
|
for checking the syntax and validity of new functions when they
|
|
are created. See under <command>CREATE LANGUAGE</command> for
|
|
further information about validators.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>lanacl</structfield></entry>
|
|
<entry><type>aclitem[]</type></entry>
|
|
<entry></entry>
|
|
<entry>Access privileges</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-largeobject">
|
|
<title><structname>pg_largeobject</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-largeobject">
|
|
<primary>pg_largeobject</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_largeobject</structname> holds the data making up
|
|
<quote>large objects</quote>. A large object is identified by an
|
|
OID assigned when it is created. Each large object is broken into
|
|
segments or <quote>pages</> small enough to be conveniently stored as rows
|
|
in <structname>pg_largeobject</structname>.
|
|
The amount of data per page is defined to be <literal>LOBLKSIZE</> (which is currently
|
|
<literal>BLCKSZ/4</>, or typically 2 kB).
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_largeobject</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>loid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry></entry>
|
|
<entry>Identifier of the large object that includes this page</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>pageno</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>Page number of this page within its large object
|
|
(counting from zero)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>data</structfield></entry>
|
|
<entry><type>bytea</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Actual data stored in the large object.
|
|
This will never be more than <symbol>LOBLKSIZE</> bytes and may be less.
|
|
</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
Each row of <structname>pg_largeobject</structname> holds data
|
|
for one page of a large object, beginning at
|
|
byte offset (<literal>pageno * LOBLKSIZE</>) within the object. The implementation
|
|
allows sparse storage: pages may be missing, and may be shorter than
|
|
<literal>LOBLKSIZE</> bytes even if they are not the last page of the object.
|
|
Missing regions within a large object read as zeroes.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-listener">
|
|
<title><structname>pg_listener</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-listener">
|
|
<primary>pg_listener</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_listener</structname> supports the <command>LISTEN</>
|
|
and <command>NOTIFY</> commands. A listener creates an entry in
|
|
<structname>pg_listener</structname> for each notification name
|
|
it is listening for. A notifier scans <structname>pg_listener</structname>
|
|
and updates each matching entry to show that a notification has occurred.
|
|
The notifier also sends a signal (using the PID recorded in the table)
|
|
to awaken the listener from sleep.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_listener</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>relname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Notify condition name. (The name need not match any actual
|
|
relation in the database; the name <structfield>relname</> is historical.)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>listenerpid</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>PID of the server process that created this entry.</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>notification</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Zero if no event is pending for this listener. If an event is
|
|
pending, the PID of the server process that sent the notification.
|
|
</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-namespace">
|
|
<title><structname>pg_namespace</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-namespace">
|
|
<primary>pg_namespace</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_namespace</> stores namespaces.
|
|
A namespace is the structure underlying SQL schemas: each namespace
|
|
can have a separate collection of relations, types, etc. without name
|
|
conflicts.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_namespace</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>nspname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Name of the namespace</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>nspowner</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-shadow"><structname>pg_shadow</structname></link>.usesysid</literal></entry>
|
|
<entry>Owner of the namespace</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>nsptablespace</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-tablespace"><structname>pg_tablespace</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
The default tablespace in which to place relations created in this
|
|
namespace. If zero, the database's default tablespace is implied.
|
|
(Changing this does not affect pre-existing relations.)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>nspacl</structfield></entry>
|
|
<entry><type>aclitem[]</type></entry>
|
|
<entry></entry>
|
|
<entry>Access privileges</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-opclass">
|
|
<title><structname>pg_opclass</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-opclass">
|
|
<primary>pg_opclass</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_opclass</structname> defines
|
|
index access method operator classes. Each operator class defines
|
|
semantics for index columns of a particular data type and a particular
|
|
index access method. Note that there can be multiple operator classes
|
|
for a given data type/access method combination, thus supporting multiple
|
|
behaviors.
|
|
</para>
|
|
|
|
<para>
|
|
Operator classes are described at length in <xref linkend="xindex">.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_opclass</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
|
|
<row>
|
|
<entry><structfield>opcamid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-am"><structname>pg_am</structname></link>.oid</literal></entry>
|
|
<entry>Index access method operator class is for</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>opcname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Name of this operator class</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>opcnamespace</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-namespace"><structname>pg_namespace</structname></link>.oid</literal></entry>
|
|
<entry>Namespace of this operator class</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>opcowner</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-shadow"><structname>pg_shadow</structname></link>.usesysid</literal></entry>
|
|
<entry>Operator class owner</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>opcintype</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
|
|
<entry>Data type that the operator class indexes</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>opcdefault</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>True if this operator class is the default for <structfield>opcintype</></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>opckeytype</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
|
|
<entry>Type of data stored in index, or zero if same as <structfield>opcintype</></entry>
|
|
</row>
|
|
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
The majority of the information defining an operator class is actually
|
|
not in its <structname>pg_opclass</structname> row, but in the associated
|
|
rows in <structname>pg_amop</structname> and
|
|
<structname>pg_amproc</structname>. Those rows are considered to be
|
|
part of the operator class definition --- this is not unlike the way
|
|
that a relation is defined by a single <structname>pg_class</structname>
|
|
row plus associated rows in <structname>pg_attribute</structname> and
|
|
other tables.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-operator">
|
|
<title><structname>pg_operator</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-operator">
|
|
<primary>pg_operator</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_operator</> stores information about operators. See
|
|
<command>CREATE OPERATOR</command> and <xref linkend="xoper"> for
|
|
details on these operator parameters.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_operator</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>oprname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Name of the operator</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>oprnamespace</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-namespace"><structname>pg_namespace</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
The OID of the namespace that contains this operator
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>oprowner</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-shadow"><structname>pg_shadow</structname></link>.usesysid</literal></entry>
|
|
<entry>Owner of the operator</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>oprkind</structfield></entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
<literal>b</> = infix (<quote>both</quote>), <literal>l</> = prefix
|
|
(<quote>left</quote>), <literal>r</> = postfix (<quote>right</quote>)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>oprcanhash</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>This operator supports hash joins</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>oprleft</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
|
|
<entry>Type of the left operand</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>oprright</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
|
|
<entry>Type of the right operand</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>oprresult</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
|
|
<entry>Type of the result</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>oprcom</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-operator"><structname>pg_operator</structname></link>.oid</literal></entry>
|
|
<entry>Commutator of this operator, if any</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>oprnegate</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-operator"><structname>pg_operator</structname></link>.oid</literal></entry>
|
|
<entry>Negator of this operator, if any</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>oprlsortop</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-operator"><structname>pg_operator</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
If this operator supports merge joins, the operator that sorts
|
|
the type of the left-hand operand (<literal>L<L</>)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>oprrsortop</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-operator"><structname>pg_operator</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
If this operator supports merge joins, the operator that sorts
|
|
the type of the right-hand operand (<literal>R<R</>)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>oprltcmpop</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-operator"><structname>pg_operator</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
If this operator supports merge joins, the less-than operator that
|
|
compares the left and right operand types (<literal>L<R</>)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>oprgtcmpop</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-operator"><structname>pg_operator</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
If this operator supports merge joins, the greater-than operator that
|
|
compares the left and right operand types (<literal>L>R</>)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>oprcode</structfield></entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
|
|
<entry>Function that implements this operator</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>oprrest</structfield></entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
|
|
<entry>Restriction selectivity estimation function for this operator</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>oprjoin</structfield></entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
|
|
<entry>Join selectivity estimation function for this operator</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
Unused column contain zeroes, for example <structfield>oprleft</structfield> is zero for a
|
|
prefix operator.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-proc">
|
|
<title><structname>pg_proc</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-proc">
|
|
<primary>pg_proc</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_proc</> stores information about functions (or procedures).
|
|
The description of <command>CREATE FUNCTION</command> and
|
|
<xref linkend="xfunc"> contain more information about the meaning of
|
|
some columns.
|
|
</para>
|
|
|
|
<para>
|
|
The table contains data for aggregate functions as well as plain functions.
|
|
If <structfield>proisagg</structfield> is true, there should be a matching
|
|
row in <structfield>pg_aggregate</structfield>.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_proc</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>proname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Name of the function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>pronamespace</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-namespace"><structname>pg_namespace</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
The OID of the namespace that contains this function
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>proowner</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-shadow"><structname>pg_shadow</structname></link>.usesysid</literal></entry>
|
|
<entry>Owner of the function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>prolang</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-language"><structname>pg_langauge</structname></link>.oid</literal></entry>
|
|
<entry>Implementation language or call interface of this function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>proisagg</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>Function is an aggregate function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>prosecdef</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>Function is a security definer (i.e., a <quote>setuid</>
|
|
function)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>proisstrict</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Function returns null if any call argument is null. In that
|
|
case the function won't actually be called at all. Functions
|
|
that are not <quote>strict</quote> must be prepared to handle
|
|
null inputs.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>proretset</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>Function returns a set (i.e., multiple values of the specified
|
|
data type)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>provolatile</structfield></entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
<structfield>provolatile</structfield> tells whether the function's
|
|
result depends only on its input arguments, or is affected by outside
|
|
factors.
|
|
It is <literal>i</literal> for <quote>immutable</> functions,
|
|
which always deliver the same result for the same inputs.
|
|
It is <literal>s</literal> for <quote>stable</> functions,
|
|
whose results (for fixed inputs) do not change within a scan.
|
|
It is <literal>v</literal> for <quote>volatile</> functions,
|
|
whose results may change at any time. (Use <literal>v</literal> also
|
|
for functions with side-effects, so that calls to them cannot get
|
|
optimized away.)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>pronargs</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>Number of arguments</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>prorettype</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
|
|
<entry>Data type of the return value</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>proargtypes</structfield></entry>
|
|
<entry><type>oidvector</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
|
|
<entry>An array with the data types of the function arguments</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>proargnames</structfield></entry>
|
|
<entry><type>text[]</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
An array with the names of the function arguments.
|
|
Arguments without a name are set to empty strings in the array.
|
|
If none of the arguments have a name, this field may be null.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>prosrc</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
This tells the function handler how to invoke the function. It
|
|
might be the actual source code of the function for interpreted
|
|
languages, a link symbol, a file name, or just about anything
|
|
else, depending on the implementation language/call convention.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>probin</structfield></entry>
|
|
<entry><type>bytea</type></entry>
|
|
<entry></entry>
|
|
<entry>Additional information about how to invoke the function.
|
|
Again, the interpretation is language-specific.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>proacl</structfield></entry>
|
|
<entry><type>aclitem[]</type></entry>
|
|
<entry></entry>
|
|
<entry>Access privileges</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
<structfield>prosrc</structfield> contains the function's C-language
|
|
name (link symbol) for compiled functions, both built-in and
|
|
dynamically loaded. For all other language types,
|
|
<structfield>prosrc</structfield> contains the function's source
|
|
text. <structfield>probin</structfield> is unused except for
|
|
dynamically-loaded C functions, for which it gives the name of the
|
|
shared library file containing the function.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="catalog-pg-rewrite">
|
|
<title><structname>pg_rewrite</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-rewrite">
|
|
<primary>pg_rewrite</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_rewrite</structname> stores rewrite rules for tables and views.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_rewrite</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>rulename</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Rule name</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>ev_class</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>The table this rule is for</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>ev_attr</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>The column this rule is for (currently, always zero to
|
|
indicate the whole table)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>ev_type</structfield></entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Event type that the rule is for: 1 = <command>SELECT</>, 2 =
|
|
<command>UPDATE</>, 3 = <command>INSERT</>, 4 =
|
|
<command>DELETE</>
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>is_instead</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>True if the rule is an <literal>INSTEAD</literal> rule</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>ev_qual</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Expression tree (in the form of a
|
|
<function>nodeToString()</function> representation) for the
|
|
rule's qualifying condition
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>ev_action</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Query tree (in the form of a
|
|
<function>nodeToString()</function> representation) for the
|
|
rule's action
|
|
</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<note>
|
|
<para>
|
|
<literal>pg_class.relhasrules</literal>
|
|
must be true if a table has any rules in this catalog.
|
|
</para>
|
|
</note>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-shadow">
|
|
<title><structname>pg_shadow</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-shadow">
|
|
<primary>pg_shadow</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_shadow</structname> contains information about
|
|
database users. The name stems from the fact that this table
|
|
should not be readable by the public since it contains passwords.
|
|
<link linkend="view-pg-user"><structname>pg_user</structname></link>
|
|
is a publicly readable view on
|
|
<structname>pg_shadow</structname> that blanks out the password field.
|
|
</para>
|
|
|
|
<para>
|
|
<xref linkend="user-manag"> contains detailed information about user and
|
|
privilege management.
|
|
</para>
|
|
|
|
<para>
|
|
Because user identities are cluster-wide,
|
|
<structname>pg_shadow</structname>
|
|
is shared across all databases of a cluster: there is only one
|
|
copy of <structname>pg_shadow</structname> per cluster, not
|
|
one per database.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_shadow</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>usename</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>User name</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>usesysid</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>User id (arbitrary number used to reference this user)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>usecreatedb</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>User may create databases</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>usesuper</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>User is a superuser</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>usecatupd</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
User may update system catalogs. (Even a superuser may not do
|
|
this unless this column is true.)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>passwd</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>Password</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>valuntil</structfield></entry>
|
|
<entry><type>abstime</type></entry>
|
|
<entry></entry>
|
|
<entry>Account expiry time (only used for password authentication)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>useconfig</structfield></entry>
|
|
<entry><type>text[]</type></entry>
|
|
<entry></entry>
|
|
<entry>Session defaults for run-time configuration variables</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-statistic">
|
|
<title><structname>pg_statistic</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-statistic">
|
|
<primary>pg_statistic</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_statistic</structname> stores statistical data
|
|
about the contents of the database. Entries are created by
|
|
<command>ANALYZE</command> and subsequently used by the query planner.
|
|
There is one entry for each table column that has been analyzed.
|
|
Note that all the statistical data is inherently approximate,
|
|
even assuming that it is up-to-date.
|
|
</para>
|
|
|
|
<para>
|
|
<structname>pg_statistic</structname> also stores statistical data about
|
|
the values of index expressions. These are described as if they were
|
|
actual data columns; in particular, <structfield>starelid</structfield>
|
|
references the index. No entry is made for an ordinary non-expression
|
|
index column, however, since it would be redundant with the entry
|
|
for the underlying table column.
|
|
</para>
|
|
|
|
<para>
|
|
Since different kinds of statistics may be appropriate for different
|
|
kinds of data, <structname>pg_statistic</structname> is designed not
|
|
to assume very much about what sort of statistics it stores. Only
|
|
extremely general statistics (such as nullness) are given dedicated
|
|
columns in <structname>pg_statistic</structname>. Everything else
|
|
is stored in <quote>slots</quote>, which are groups of associated columns
|
|
whose content is identified by a code number in one of the slot's columns.
|
|
For more information see
|
|
<filename>src/include/catalog/pg_statistic.h</filename>.
|
|
</para>
|
|
|
|
<para>
|
|
<structname>pg_statistic</structname> should not be readable by the
|
|
public, since even statistical information about a table's contents
|
|
may be considered sensitive. (Example: minimum and maximum values
|
|
of a salary column might be quite interesting.)
|
|
<link linkend="view-pg-stats"><structname>pg_stats</structname></link>
|
|
is a publicly readable view on
|
|
<structname>pg_statistic</structname> that only exposes information
|
|
about those tables that are readable by the current user.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_statistic</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>starelid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>The table or index that the described column belongs to</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>staattnum</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-attribute"><structname>pg_attribute</structname></link>.attnum</literal></entry>
|
|
<entry>The number of the described column</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>stanullfrac</structfield></entry>
|
|
<entry><type>float4</type></entry>
|
|
<entry></entry>
|
|
<entry>The fraction of the column's entries that are null</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>stawidth</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>The average stored width, in bytes, of nonnull entries</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>stadistinct</structfield></entry>
|
|
<entry><type>float4</type></entry>
|
|
<entry></entry>
|
|
<entry>The number of distinct nonnull data values in the column.
|
|
A value greater than zero is the actual number of distinct values.
|
|
A value less than zero is the negative of a fraction of the number
|
|
of rows in the table (for example, a column in which values appear about
|
|
twice on the average could be represented by <structfield>stadistinct</> = -0.5).
|
|
A zero value means the number of distinct values is unknown.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>stakind<replaceable>N</></structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
A code number indicating the kind of statistics stored in the
|
|
<replaceable>N</>th <quote>slot</quote> of the
|
|
<structname>pg_statistic</structname> row.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>staop<replaceable>N</></structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-operator"><structname>pg_operator</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
An operator used to derive the statistics stored in the
|
|
<replaceable>N</>th <quote>slot</quote>. For example, a
|
|
histogram slot would show the <literal><</literal> operator
|
|
that defines the sort order of the data.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>stanumbers<replaceable>N</></structfield></entry>
|
|
<entry><type>float4[]</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Numerical statistics of the appropriate kind for the
|
|
<replaceable>N</>th <quote>slot</quote>, or null if the slot
|
|
kind does not involve numerical values.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>stavalues<replaceable>N</></structfield></entry>
|
|
<entry><type>anyarray</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Column data values of the appropriate kind for the
|
|
<replaceable>N</>th <quote>slot</quote>, or null if the slot
|
|
kind does not store any data values. Each array's element
|
|
values are actually of the specific column's data type, so there
|
|
is no way to define these columns' type more specifically than
|
|
<type>anyarray</>.
|
|
</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-tablespace">
|
|
<title><structname>pg_tablespace</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-tablespace">
|
|
<primary>pg_tablespace</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_tablespace</structname> stores information
|
|
about the available tablespaces. Tables can be placed in particular
|
|
tablespaces to aid administration of disk layout.
|
|
</para>
|
|
|
|
<para>
|
|
Unlike most system catalogs, <structname>pg_tablespace</structname>
|
|
is shared across all databases of a cluster: there is only one
|
|
copy of <structname>pg_tablespace</structname> per cluster, not
|
|
one per database.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_tablespace</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>spcname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Tablespace name</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>spcowner</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-shadow"><structname>pg_shadow</structname></link>.usesysid</literal></entry>
|
|
<entry>Owner of the tablespace, usually the user who created it</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>spclocation</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>Location (directory path) of the tablespace</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>spcacl</structfield></entry>
|
|
<entry><type>aclitem[]</type></entry>
|
|
<entry></entry>
|
|
<entry>Access privileges</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-trigger">
|
|
<title><structname>pg_trigger</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-trigger">
|
|
<primary>pg_trigger</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_trigger</structname> stores triggers on tables. See under
|
|
<command>CREATE TRIGGER</command> for more information.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_trigger</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>tgrelid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>The table this trigger is on</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>tgname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Trigger name (must be unique among triggers of same table)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>tgfoid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
|
|
<entry>The function to be called</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>tgtype</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>Bit mask identifying trigger conditions</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>tgenabled</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>True if trigger is enabled (not presently checked everywhere
|
|
it should be, so disabling a trigger by setting this false does not
|
|
work reliably)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>tgisconstraint</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>True if trigger implements a referential integrity constraint</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>tgconstrname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Referential integrity constraint name</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>tgconstrrelid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>The table referenced by an referential integrity constraint</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>tgdeferrable</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>True if deferrable</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>tginitdeferred</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>True if initially deferred</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>tgnargs</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>Number of argument strings passed to trigger function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>tgattr</structfield></entry>
|
|
<entry><type>int2vector</type></entry>
|
|
<entry></entry>
|
|
<entry>Currently unused</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>tgargs</structfield></entry>
|
|
<entry><type>bytea</type></entry>
|
|
<entry></entry>
|
|
<entry>Argument strings to pass to trigger, each null-terminated</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<note>
|
|
<para>
|
|
<literal>pg_class.reltriggers</literal> needs to match up with the
|
|
entries in this table.
|
|
</para>
|
|
</note>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-type">
|
|
<title><structname>pg_type</structname></title>
|
|
|
|
<indexterm zone="catalog-pg-type">
|
|
<primary>pg_type</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The catalog <structname>pg_type</structname> stores information about data types. Base types
|
|
(scalar types) are created with <command>CREATE TYPE</command>.
|
|
A composite type is automatically created for each table in the database, to
|
|
represent the row structure of the table. It is also possible to create
|
|
composite types with <command>CREATE TYPE AS</command> and
|
|
domains with <command>CREATE DOMAIN</command>.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_type</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>typname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Data type name</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typnamespace</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-namespace"><structname>pg_namespace</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
The OID of the namespace that contains this type
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typowner</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-shadow"><structname>pg_shadow</structname></link>.usesysid</literal></entry>
|
|
<entry>Owner of the type</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typlen</structfield></entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
For a fixed-size type, <structfield>typlen</structfield> is the number
|
|
of bytes in the internal representation of the type. But for a
|
|
variable-length type, <structfield>typlen</structfield> is negative.
|
|
-1 indicates a <quote>varlena</> type (one that has a length word),
|
|
-2 indicates a null-terminated C string.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typbyval</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
<structfield>typbyval</structfield> determines whether internal
|
|
routines pass a value of this type by value or by reference.
|
|
<structfield>typbyval</structfield> had better be false if
|
|
<structfield>typlen</structfield> is not 1, 2, or 4 (or 8 on machines
|
|
where Datum is 8 bytes).
|
|
Variable-length types are always passed by reference. Note that
|
|
<structfield>typbyval</structfield> can be false even if the
|
|
length would allow pass-by-value; this is currently true for
|
|
type <type>float4</type>, for example.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typtype</structfield></entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
<structfield>typtype</structfield> is <literal>b</literal> for
|
|
a base type, <literal>c</literal> for a composite type (e.g., a
|
|
table's row type), <literal>d</literal> for a domain, or
|
|
<literal>p</literal> for a pseudo-type. See also
|
|
<structfield>typrelid</structfield> and
|
|
<structfield>typbasetype</structfield>.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typisdefined</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
True if the type is defined, false if this is a placeholder
|
|
entry for a not-yet-defined type. When
|
|
<structfield>typisdefined</structfield> is false, nothing
|
|
except the type name, namespace, and OID can be relied on.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typdelim</structfield></entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>Character that separates two values of this type when parsing
|
|
array input. Note that the delimiter is associated with the array
|
|
element data type, not the array data type.</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typrelid</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
If this is a composite type (see
|
|
<structfield>typtype</structfield>), then this column points to
|
|
the <structname>pg_class</structname> entry that defines the
|
|
corresponding table. (For a free-standing composite type, the
|
|
<structname>pg_class</structname> entry doesn't really represent
|
|
a table, but it is needed anyway for the type's
|
|
<structname>pg_attribute</structname> entries to link to.)
|
|
Zero for non-composite types.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typelem</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
If <structfield>typelem</structfield> is not 0 then it
|
|
identifies another row in <structname>pg_type</structname>.
|
|
The current type can then be subscripted like an array yielding
|
|
values of type <structfield>typelem</structfield>. A
|
|
<quote>true</quote> array type is variable length
|
|
(<structfield>typlen</structfield> = -1),
|
|
but some fixed-length (<structfield>typlen</structfield> > 0) types
|
|
also have nonzero <structfield>typelem</structfield>, for example
|
|
<type>name</type> and <type>oidvector</type>.
|
|
If a fixed-length type has a <structfield>typelem</structfield> then
|
|
its internal representation must be some number of values of the
|
|
<structfield>typelem</structfield> data type with no other data.
|
|
Variable-length array types have a header defined by the array
|
|
subroutines.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typinput</structfield></entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
|
|
<entry>Input conversion function (text format)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typoutput</structfield></entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
|
|
<entry>Output conversion function (text format)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typreceive</structfield></entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
|
|
<entry>Input conversion function (binary format), or 0 if none</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typsend</structfield></entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
|
|
<entry>Output conversion function (binary format), or 0 if none</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typanalyze</structfield></entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
|
|
<entry>Custom ANALYZE function, or 0 to use the standard function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typalign</structfield></entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry><para>
|
|
|
|
<structfield>typalign</structfield> is the alignment required
|
|
when storing a value of this type. It applies to storage on
|
|
disk as well as most representations of the value inside
|
|
<productname>PostgreSQL</>.
|
|
When multiple values are stored consecutively, such
|
|
as in the representation of a complete row on disk, padding is
|
|
inserted before a datum of this type so that it begins on the
|
|
specified boundary. The alignment reference is the beginning
|
|
of the first datum in the sequence.
|
|
</para><para>
|
|
Possible values are:
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para><literal>c</> = <type>char</type> alignment, i.e., no alignment needed.</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para><literal>s</> = <type>short</type> alignment (2 bytes on most machines).</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para><literal>i</> = <type>int</type> alignment (4 bytes on most machines).</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para><literal>d</> = <type>double</type> alignment (8 bytes on many machines, but by no means all).</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
</para><note>
|
|
<para>
|
|
For types used in system tables, it is critical that the size
|
|
and alignment defined in <structname>pg_type</structname>
|
|
agree with the way that the compiler will lay out the column in
|
|
a structure representing a table row.
|
|
</para>
|
|
</note></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typstorage</structfield></entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry><para>
|
|
<structfield>typstorage</structfield> tells for varlena
|
|
types (those with <structfield>typlen</structfield> = -1) if
|
|
the type is prepared for toasting and what the default strategy
|
|
for attributes of this type should be.
|
|
Possible values are
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para><literal>p</>: Value must always be stored plain.</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
<literal>e</>: Value can be stored in a <quote>secondary</quote>
|
|
relation (if relation has one, see
|
|
<literal>pg_class.reltoastrelid</literal>).
|
|
</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para><literal>m</>: Value can be stored compressed inline.</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para><literal>x</>: Value can be stored compressed inline or stored in <quote>secondary</quote> storage.</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
Note that <literal>m</> columns can also be moved out to secondary
|
|
storage, but only as a last resort (<literal>e</> and <literal>x</> columns are
|
|
moved first).
|
|
</para></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typnotnull</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry><para>
|
|
<structfield>typnotnull</structfield> represents a not-null
|
|
constraint on a type. Used for domains only.
|
|
</para></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typbasetype</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
|
|
<entry><para>
|
|
If this is a domain (see <structfield>typtype</structfield>),
|
|
then <structfield>typbasetype</structfield> identifies
|
|
the type that this one is based on. Zero if not a domain.
|
|
</para></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typtypmod</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry><para>
|
|
Domains use <structfield>typtypmod</structfield> to record the <literal>typmod</>
|
|
to be applied to their base type (-1 if base type does not use a
|
|
<literal>typmod</>). -1 if this type is not a domain.
|
|
</para></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typndims</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry><para>
|
|
<structfield>typndims</structfield> is the number of array dimensions
|
|
for a domain that is an array (that is, <structfield>typbasetype</> is an array type;
|
|
the domain's <structfield>typelem</> will match the base type's <structfield>typelem</structfield>).
|
|
Zero for types other than array domains.
|
|
</para></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typdefaultbin</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry><para>
|
|
If <structfield>typdefaultbin</> is not null, it is the <function>nodeToString()</function>
|
|
representation of a default expression for the type. This is
|
|
only used for domains.
|
|
</para></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>typdefault</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry><para>
|
|
<structfield>typdefault</> is null if the type has no associated
|
|
default value. If <structfield>typdefaultbin</> is not null,
|
|
<structfield>typdefault</> must contain a human-readable version of the
|
|
default expression represented by <structfield>typdefaultbin</>. If
|
|
<structfield>typdefaultbin</> is null and <structfield>typdefault</> is
|
|
not, then <structfield>typdefault</> is the external representation of
|
|
the type's default value, which may be fed to the type's input
|
|
converter to produce a constant.
|
|
</para></entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
</sect1>
|
|
|
|
<sect1 id="views-overview">
|
|
<title>System Views</title>
|
|
|
|
<para>
|
|
In addition to the system catalogs, <productname>PostgreSQL</productname>
|
|
provides a number of built-in views. The system views provide convenient
|
|
access to some commonly used queries on the system catalogs. Some of these
|
|
views provide access to internal server state, as well.
|
|
</para>
|
|
|
|
<para>
|
|
<xref linkend="view-table"> lists the system views described here.
|
|
More detailed documentation of each view follows below.
|
|
There are some additional views that provide access to the results of
|
|
the statistics collector; they are described in <xref
|
|
linkend="monitoring-stats-views-table">.
|
|
</para>
|
|
|
|
<para>
|
|
The information schema (<xref linkend="information-schema">) provides
|
|
an alternative set of views which overlap the functionality of the system
|
|
views. Since the information schema is SQL-standard whereas the views
|
|
described here are <productname>PostgreSQL</productname>-specific,
|
|
it's usually better to use the information schema if it provides all
|
|
the information you need.
|
|
</para>
|
|
|
|
<para>
|
|
Except where noted, all the views described here are read-only.
|
|
</para>
|
|
|
|
<table id="view-table">
|
|
<title>System Views</title>
|
|
|
|
<tgroup cols="2">
|
|
<thead>
|
|
<row>
|
|
<entry>View Name</entry>
|
|
<entry>Purpose</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><link linkend="view-pg-indexes"><structname>pg_indexes</structname></link></entry>
|
|
<entry>indexes</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="view-pg-locks"><structname>pg_locks</structname></link></entry>
|
|
<entry>currently held locks</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="view-pg-rules"><structname>pg_rules</structname></link></entry>
|
|
<entry>rules</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="view-pg-settings"><structname>pg_settings</structname></link></entry>
|
|
<entry>parameter settings</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="view-pg-stats"><structname>pg_stats</structname></link></entry>
|
|
<entry>planner statistics</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="view-pg-tables"><structname>pg_tables</structname></link></entry>
|
|
<entry>tables</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="view-pg-user"><structname>pg_user</structname></link></entry>
|
|
<entry>database users</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="view-pg-views"><structname>pg_views</structname></link></entry>
|
|
<entry>views</entry>
|
|
</row>
|
|
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
</sect1>
|
|
|
|
<sect1 id="view-pg-indexes">
|
|
<title><structname>pg_indexes</structname></title>
|
|
|
|
<indexterm zone="view-pg-indexes">
|
|
<primary>pg_indexes</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The view <structname>pg_indexes</structname> provides access to
|
|
useful information about each index in the database.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_indexes</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>schemaname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-namespace"><structname>pg_namespace</structname></link>.nspname</literal></entry>
|
|
<entry>name of schema containing table and index</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>tablename</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.relname</literal></entry>
|
|
<entry>name of table the index is for</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>indexname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.relname</literal></entry>
|
|
<entry>name of index</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>indexdef</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>index definition (a reconstructed creation command)</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="view-pg-locks">
|
|
<title><structname>pg_locks</structname></title>
|
|
|
|
<indexterm zone="view-pg-locks">
|
|
<primary>pg_locks</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The view <structname>pg_locks</structname> provides access to
|
|
information about the locks held by open transactions within the
|
|
database server. See <xref linkend="mvcc"> for more discussion
|
|
of locking.
|
|
</para>
|
|
|
|
<para>
|
|
<structname>pg_locks</structname> contains one row per active lockable
|
|
object, requested lock mode, and relevant transaction. Thus, the same
|
|
lockable object may
|
|
appear many times, if multiple transactions are holding or waiting
|
|
for locks on it. However, an object that currently has no locks on it
|
|
will not appear at all. A lockable object is either a relation (e.g., a
|
|
table) or a transaction ID.
|
|
</para>
|
|
|
|
<para>
|
|
Note that this view includes only table-level
|
|
locks, not row-level ones. If a transaction is waiting for a
|
|
row-level lock, it will appear in the view as waiting for the
|
|
transaction ID of the current holder of that row lock.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_locks</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>relation</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
OID of the locked relation, or NULL if the lockable object
|
|
is a transaction ID
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>database</structfield></entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-database"><structname>pg_database</structname></link>.oid</literal></entry>
|
|
<entry>
|
|
OID of the database in which the locked relation exists, or
|
|
zero if the locked relation is a globally-shared table, or
|
|
NULL if the lockable object is a transaction ID
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>transaction</structfield></entry>
|
|
<entry><type>xid</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
ID of a transaction, or NULL if the lockable object is a relation
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>pid</structfield></entry>
|
|
<entry><type>integer</type></entry>
|
|
<entry></entry>
|
|
<entry>process ID of a server process holding or awaiting this
|
|
lock</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>mode</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>name of the lock mode held or desired by this process (see <xref
|
|
linkend="locking-tables">)</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>granted</structfield></entry>
|
|
<entry><type>boolean</type></entry>
|
|
<entry></entry>
|
|
<entry>true if lock is held, false if lock is awaited</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
<structfield>granted</structfield> is true in a row representing a lock
|
|
held by the indicated session. False indicates that this session is
|
|
currently waiting to acquire this lock, which implies that some other
|
|
session is holding a conflicting lock mode on the same lockable object.
|
|
The waiting session will sleep until the other lock is released (or a
|
|
deadlock situation is detected). A single session can be waiting to acquire
|
|
at most one lock at a time.
|
|
</para>
|
|
|
|
<para>
|
|
Every transaction holds an exclusive lock on its transaction ID for its
|
|
entire duration. If one transaction finds it necessary to wait specifically
|
|
for another transaction, it does so by attempting to acquire share lock on
|
|
the other transaction ID. That will succeed only when the other transaction
|
|
terminates and releases its locks.
|
|
</para>
|
|
|
|
<para>
|
|
When the <structname>pg_locks</structname> view is accessed, the
|
|
internal lock manager data structures are momentarily locked, and
|
|
a copy is made for the view to display. This ensures that the
|
|
view produces a consistent set of results, while not blocking
|
|
normal lock manager operations longer than necessary. Nonetheless
|
|
there could be some impact on database performance if this view is
|
|
read often.
|
|
</para>
|
|
|
|
<para>
|
|
<structname>pg_locks</structname> provides a global view of all locks
|
|
in the database cluster, not only those relevant to the current database.
|
|
Although its <structfield>relation</structfield> column can be joined
|
|
against <structname>pg_class</>.<structfield>oid</> to identify locked
|
|
relations, this will only work correctly for relations in the current
|
|
database (those for which the <structfield>database</structfield> column
|
|
is either the current database's OID or zero).
|
|
</para>
|
|
|
|
<para>
|
|
If you have enabled the statistics collector, the
|
|
<structfield>pid</structfield> column can be joined to the
|
|
<structfield>procpid</structfield> column of the
|
|
<structname>pg_stat_activity</structname> view to get more
|
|
information on the session holding or waiting to hold the lock.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="view-pg-rules">
|
|
<title><structname>pg_rules</structname></title>
|
|
|
|
<indexterm zone="view-pg-rules">
|
|
<primary>pg_rules</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The view <structname>pg_rules</structname> provides access to
|
|
useful information about query rewrite rules.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_rules</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>schemaname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-namespace"><structname>pg_namespace</structname></link>.nspname</literal></entry>
|
|
<entry>name of schema containing table</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>tablename</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.relname</literal></entry>
|
|
<entry>name of table the rule is for</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>rulename</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-rewrite"><structname>pg_rewrite</structname></link>.rulename</literal></entry>
|
|
<entry>name of rule</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>definition</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>rule definition (a reconstructed creation command)</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
The <structname>pg_rules</structname> view excludes the ON SELECT rules of
|
|
views; those can be seen in <structname>pg_views</structname>.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="view-pg-settings">
|
|
<title><structname>pg_settings</structname></title>
|
|
|
|
<indexterm zone="view-pg-settings">
|
|
<primary>pg_settings</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The view <structname>pg_settings</structname> provides access to
|
|
run-time parameters of the server. It is essentially an alternative
|
|
interface to the <command>SHOW</> and <command>SET</> commands.
|
|
It also provides access to some facts about each parameter that are
|
|
not directly available from <command>SHOW</>, such as minimum and
|
|
maximum values.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_settings</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>name</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>run-time configuration parameter name</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>setting</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>current value of the parameter</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>category</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>logical group of the parameter</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>short_desc</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>a brief description of the parameter</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>extra_desc</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>additional, more detailed, information about the parameter</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>context</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>context required to set the parameter's value</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>vartype</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>parameter type (<literal>bool</>, <literal>integer</>,
|
|
<literal>real</>, or <literal>string</>)
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>source</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>source of the current parameter value</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>min_val</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>minimum allowed value of the parameter (NULL for nonnumeric
|
|
values)</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>max_val</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>maximum allowed value of the parameter (NULL for nonnumeric
|
|
values)</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
The <structname>pg_settings</structname> view cannot be inserted into or
|
|
deleted from, but it can be updated. An <command>UPDATE</command> applied
|
|
to a row of <structname>pg_settings</structname> is equivalent to executing
|
|
the <xref linkend="SQL-SET" endterm="SQL-SET-title"> command on that named
|
|
parameter. The change only affects the value used by the current
|
|
session. If an <command>UPDATE</command> is issued within a transaction
|
|
that is later aborted, the effects of the <command>UPDATE</command> command
|
|
disappear when the transaction is rolled back. Once the surrounding
|
|
transaction is committed, the effects will persist until the end of the
|
|
session, unless overridden by another <command>UPDATE</command> or
|
|
<command>SET</command>.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="view-pg-stats">
|
|
<title><structname>pg_stats</structname></title>
|
|
|
|
<indexterm zone="view-pg-stats">
|
|
<primary>pg_stats</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The view <structname>pg_stats</structname> provides access to
|
|
the information stored in the <link
|
|
linkend="catalog-pg-statistic"><structname>pg_statistic</structname></link>
|
|
catalog. This view allows access only to rows of
|
|
<structname>pg_statistic</structname> that correspond to tables the
|
|
user has permission to read, and therefore it is safe to allow public
|
|
read access to this view.
|
|
</para>
|
|
|
|
<para>
|
|
<structname>pg_stats</structname> is also designed to present the
|
|
information in a more readable format than the underlying catalog
|
|
--- at the cost that its schema must be extended whenever new slot types
|
|
are defined for <structname>pg_statistic</structname>.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_stats</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>schemaname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-namespace"><structname>pg_namespace</structname></link>.nspname</literal></entry>
|
|
<entry>name of schema containing table</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>tablename</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.relname</literal></entry>
|
|
<entry>name of table</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>attname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-attribute"><structname>pg_attribute</structname></link>.attname</literal></entry>
|
|
<entry>name of the column described by this row</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>null_frac</structfield></entry>
|
|
<entry><type>real</type></entry>
|
|
<entry></entry>
|
|
<entry>fraction of column entries that are null</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>avg_width</structfield></entry>
|
|
<entry><type>integer</type></entry>
|
|
<entry></entry>
|
|
<entry>average width in bytes of column's entries</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>n_distinct</structfield></entry>
|
|
<entry><type>real</type></entry>
|
|
<entry></entry>
|
|
<entry>If greater than zero, the estimated number of distinct values
|
|
in the column. If less than zero, the negative of the number of
|
|
distinct values divided by the number of rows. (The negated form
|
|
is used when <command>ANALYZE</> believes that the number of distinct
|
|
values
|
|
is likely to increase as the table grows; the positive form is used
|
|
when the column seems to have a fixed number of possible values.)
|
|
For example, -1 indicates a unique column in which the number of
|
|
distinct values is the same as the number of rows.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>most_common_vals</structfield></entry>
|
|
<entry><type>anyarray</type></entry>
|
|
<entry></entry>
|
|
<entry>A list of the most common values in the column. (NULL if
|
|
no values seem to be more common than any others.)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>most_common_freqs</structfield></entry>
|
|
<entry><type>real[]</type></entry>
|
|
<entry></entry>
|
|
<entry>A list of the frequencies of the most common values,
|
|
i.e., number of occurrences of each divided by total number of rows.
|
|
(NULL when <structfield>most_common_vals</structfield> is.)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>histogram_bounds</structfield></entry>
|
|
<entry><type>anyarray</type></entry>
|
|
<entry></entry>
|
|
<entry>A list of values that divide the column's values into
|
|
groups of approximately equal population. The values in
|
|
<structfield>most_common_vals</>, if present, are omitted from this
|
|
histogram calculation. (This column is NULL if the column data type
|
|
does not have a <literal><</> operator or if the
|
|
<structfield>most_common_vals</> list accounts for the entire
|
|
population.)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>correlation</structfield></entry>
|
|
<entry><type>real</type></entry>
|
|
<entry></entry>
|
|
<entry>Statistical correlation between physical row ordering and
|
|
logical ordering of the column values. This ranges from -1 to +1.
|
|
When the value is near -1 or +1, an index scan on the column will
|
|
be estimated to be cheaper than when it is near zero, due to reduction
|
|
of random access to the disk. (This column is NULL if the column data
|
|
type does not have a <literal><</> operator.)
|
|
</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
The maximum number of entries in the <structfield>most_common_vals</>
|
|
and <structfield>histogram_bounds</> arrays can be set on a
|
|
column-by-column basis using the <command>ALTER TABLE SET STATISTICS</>
|
|
command, or globally by setting the
|
|
<varname>default_statistics_target</varname> runtime parameter.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="view-pg-tables">
|
|
<title><structname>pg_tables</structname></title>
|
|
|
|
<indexterm zone="view-pg-tables">
|
|
<primary>pg_tables</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The view <structname>pg_tables</structname> provides access to
|
|
useful information about each table in the database.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_tables</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>schemaname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-namespace"><structname>pg_namespace</structname></link>.nspname</literal></entry>
|
|
<entry>name of schema containing table</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>tablename</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.relname</literal></entry>
|
|
<entry>name of table</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>tableowner</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-shadow"><structname>pg_shadow</structname></link>.usename</literal></entry>
|
|
<entry>name of table's owner</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>hasindexes</structfield></entry>
|
|
<entry><type>boolean</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.relhasindex</literal></entry>
|
|
<entry>true if table has (or recently had) any indexes</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>hasrules</structfield></entry>
|
|
<entry><type>boolean</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.relhasrules</literal></entry>
|
|
<entry>true if table has rules</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>hastriggers</structfield></entry>
|
|
<entry><type>boolean</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.reltriggers</literal></entry>
|
|
<entry>true if table has triggers</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="view-pg-user">
|
|
<title><structname>pg_user</structname></title>
|
|
|
|
<indexterm zone="view-pg-user">
|
|
<primary>pg_user</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The view <structname>pg_user</structname> provides access to
|
|
information about database users. This is simply a publicly
|
|
readable view of
|
|
<link linkend="catalog-pg-shadow"><structname>pg_shadow</structname></link>
|
|
that blanks out the password field.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_user</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>usename</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>User name</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>usesysid</structfield></entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>User id (arbitrary number used to reference this user)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>usecreatedb</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>User may create databases</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>usesuper</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>User is a superuser</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>usecatupd</structfield></entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
User may update system catalogs. (Even a superuser may not do
|
|
this unless this column is true.)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>passwd</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>Not the password (always reads as <literal>********</>)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>valuntil</structfield></entry>
|
|
<entry><type>abstime</type></entry>
|
|
<entry></entry>
|
|
<entry>Account expiry time (only used for password authentication)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><structfield>useconfig</structfield></entry>
|
|
<entry><type>text[]</type></entry>
|
|
<entry></entry>
|
|
<entry>Session defaults for run-time configuration variables</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="view-pg-views">
|
|
<title><structname>pg_views</structname></title>
|
|
|
|
<indexterm zone="view-pg-views">
|
|
<primary>pg_views</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The view <structname>pg_views</structname> provides access to
|
|
useful information about each view in the database.
|
|
</para>
|
|
|
|
<table>
|
|
<title><structname>pg_views</> Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry><structfield>schemaname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-namespace"><structname>pg_namespace</structname></link>.nspname</literal></entry>
|
|
<entry>name of schema containing view</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>viewname</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.relname</literal></entry>
|
|
<entry>name of view</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>viewowner</structfield></entry>
|
|
<entry><type>name</type></entry>
|
|
<entry><literal><link linkend="catalog-pg-shadow"><structname>pg_shadow</structname></link>.usename</literal></entry>
|
|
<entry>name of view's owner</entry>
|
|
</row>
|
|
<row>
|
|
<entry><structfield>definition</structfield></entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>view definition (a reconstructed SELECT query)</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
</chapter>
|
|
|
|
<!-- Keep this comment at the end of the file
|
|
Local variables:
|
|
mode:sgml
|
|
sgml-omittag:nil
|
|
sgml-shorttag:t
|
|
sgml-minimize-attributes:nil
|
|
sgml-always-quote-attributes:t
|
|
sgml-indent-step:1
|
|
sgml-indent-tabs-mode:nil
|
|
sgml-indent-data:t
|
|
sgml-parent-document:nil
|
|
sgml-default-dtd-file:"./reference.ced"
|
|
sgml-exposed-tags:nil
|
|
sgml-local-catalogs:("/usr/share/sgml/catalog")
|
|
sgml-local-ecat-files:nil
|
|
End:
|
|
-->
|