mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-08-21 23:23:24 +02:00
including: - replacing all the appropriate usages of <citetitle>PostgreSQL ...</citetitle> with &cite-user;, &cite-admin;, and so on - fix an omission in the EXECUTE documentation - add some more text to the EXPLAIN documentation - improve the PL/PgSQL RETURN NEXT documentation (more work to do here) - minor markup fixes Neil Conway
3524 lines
96 KiB
Plaintext
3524 lines
96 KiB
Plaintext
<!--
|
|
Documentation of the system catalogs, directed toward PostgreSQL developers
|
|
$Header: /cvsroot/pgsql/doc/src/sgml/catalogs.sgml,v 2.65 2003/01/19 00:13:28 momjian Exp $
|
|
-->
|
|
|
|
<chapter id="catalogs">
|
|
<title>System Catalogs</title>
|
|
|
|
<sect1 id="catalogs-overview">
|
|
<title>Overview</title>
|
|
|
|
<para>
|
|
The system catalogs are the place where a relational database
|
|
management system stores schema metadata, such as information about
|
|
tables and columns, and internal bookkeeping information.
|
|
<productname>PostgreSQL</productname>'s system catalogs are regular
|
|
tables. You can drop and recreate the tables, add columns, insert
|
|
and update values, and severely mess up your system that way.
|
|
Normally one should not change the system catalogs by hand, there
|
|
are always SQL commands to do that. (For example, <command>CREATE
|
|
DATABASE</command> inserts a row into the
|
|
<structname>pg_database</structname> catalog -- and actually
|
|
creates the database on disk.) There are some exceptions for
|
|
especially esoteric operations, such as adding index access methods.
|
|
</para>
|
|
<para>
|
|
Most system catalogs are copied from the template database during
|
|
database creation, and are thereafter database-specific. A few
|
|
catalogs are physically shared across all databases in an installation;
|
|
these are marked in the descriptions of the individual catalogs.
|
|
</para>
|
|
|
|
<table>
|
|
<title>System Catalogs</title>
|
|
|
|
<tgroup cols="2">
|
|
<thead>
|
|
<row>
|
|
<entry>Catalog Name</entry>
|
|
<entry>Purpose</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><link linkend="catalog-pg-aggregate">
|
|
<database class="table">pg_aggregate</database></link></entry>
|
|
<entry>aggregate functions</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>pg_am</entry>
|
|
<entry>index access methods</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>pg_amop</entry>
|
|
<entry>access method operators</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>pg_amproc</entry>
|
|
<entry>access method support procedures</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-attrdef">
|
|
<database class="table">pg_attrdef</database></link></entry>
|
|
<entry>column default values</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-attribute">
|
|
<database class="table">pg_attribute</database></link></entry>
|
|
<entry>table columns (<quote>attributes</quote>, <quote>fields</quote>)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-cast">
|
|
<database class="table">pg_cast</database></link></entry>
|
|
<entry>casts (data type conversions)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-class">
|
|
<database class="table">pg_class</database></link></entry>
|
|
<entry>tables, indexes, sequences (<quote>relations</quote>)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-constraint">
|
|
<database class="table">pg_constraint</database></link></entry>
|
|
<entry>check constraints, unique / primary key constraints, foreign key constraints</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-conversion">
|
|
<database class="table">pg_conversion</database></link></entry>
|
|
<entry>encoding conversion information</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-database">
|
|
<database class="table">pg_database</database></link></entry>
|
|
<entry>databases within this database cluster</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-depend">
|
|
<database class="table">pg_depend</database></link></entry>
|
|
<entry>dependencies between database objects</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-description">
|
|
<database class="table">pg_description</database></link></entry>
|
|
<entry>descriptions or comments on database objects</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-group">
|
|
<database class="table">pg_group</database></link></entry>
|
|
<entry>groups of database users</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-index">
|
|
<database class="table">pg_index</database></link></entry>
|
|
<entry>additional index information</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-inherits">
|
|
<database class="table">pg_inherits</database></link></entry>
|
|
<entry>table inheritance hierarchy</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-language">
|
|
<database class="table">pg_language</database></link></entry>
|
|
<entry>languages for writing functions</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-largeobject">
|
|
<database class="table">pg_largeobject</database></link></entry>
|
|
<entry>large objects</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-listener">
|
|
<database class="table">pg_listener</database></link></entry>
|
|
<entry>asynchronous notification</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-namespace">
|
|
<database class="table">pg_namespace</database></link></entry>
|
|
<entry>namespaces (schemas)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-opclass">
|
|
<database class="table">pg_opclass</database></link></entry>
|
|
<entry>index access method operator classes</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-operator">
|
|
<database class="table">pg_operator</database></link></entry>
|
|
<entry>operators</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-proc">
|
|
<database class="table">pg_proc</database></link></entry>
|
|
<entry>functions and procedures</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-rewrite">
|
|
<database class="table">pg_rewrite</database></link></entry>
|
|
<entry>query rewriter rules</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-shadow">
|
|
<database class="table">pg_shadow</database></link></entry>
|
|
<entry>database users</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-statistic">
|
|
<database class="table">pg_statistic</database></link></entry>
|
|
<entry>optimizer statistics</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-trigger">
|
|
<database class="table">pg_trigger</database></link></entry>
|
|
<entry>triggers</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><link linkend="catalog-pg-type">
|
|
<database class="table">pg_type</database></link></entry>
|
|
<entry>data types</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
More detailed documentation of each catalog follows below.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-aggregate">
|
|
<title>pg_aggregate</title>
|
|
|
|
<para>
|
|
<structname>pg_aggregate</structname> stores information about
|
|
aggregate functions. An aggregate function is a function that
|
|
operates on a set of values (typically one column from each row
|
|
that matches a query condition) and returns a single value computed
|
|
from all these values. Typical aggregate functions are
|
|
<function>sum</function>, <function>count</function>, and
|
|
<function>max</function>. Each entry in
|
|
<structname>pg_aggregate</structname> is an extension of an entry
|
|
in <structname>pg_proc</structname>. The <structname>pg_proc</structname>
|
|
entry carries the aggregate's name, input and output datatypes, and
|
|
other information that is similar to ordinary functions.
|
|
</para>
|
|
|
|
<table>
|
|
<title>pg_aggregate Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry>aggfnoid</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry>pg_proc OID of the aggregate function</entry>
|
|
</row>
|
|
<row>
|
|
<entry>aggtransfn</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry>Transition function</entry>
|
|
</row>
|
|
<row>
|
|
<entry>aggfinalfn</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry>Final function (zero if none)</entry>
|
|
</row>
|
|
<row>
|
|
<entry>aggtranstype</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_type.oid</entry>
|
|
<entry>The type of the aggregate function's internal transition (state) data</entry>
|
|
</row>
|
|
<row>
|
|
<entry>agginitval</entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
The initial value of the transition state. This is a text
|
|
field containing the initial value in its external string
|
|
representation. If the field is NULL, the transition state
|
|
value starts out NULL.
|
|
</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
New aggregate functions are registered with the <command>CREATE
|
|
AGGREGATE</command> command. See the &cite-programmer; for more
|
|
information about writing aggregate functions and the meaning of
|
|
the transition functions, etc.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-am">
|
|
<title>pg_am</title>
|
|
|
|
<para>
|
|
<structname>pg_am</structname> stores information about index access
|
|
methods. There is one row for each index access method supported by
|
|
the system.
|
|
</para>
|
|
|
|
<table>
|
|
<title>pg_am Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
|
|
<row>
|
|
<entry>amname</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>name of the access method</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amowner</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry>pg_shadow.usesysid</entry>
|
|
<entry>user ID of the owner (currently not used)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amstrategies</entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>number of operator strategies for this access method</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amsupport</entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>number of support routines for this access method</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amorderstrategy</entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>zero if the index offers no sort order, otherwise the strategy
|
|
number of the strategy operator that describes the sort order</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amcanunique</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>does AM support unique indexes?</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amcanmulticol</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>does AM support multicolumn indexes?</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amindexnulls</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>does AM support NULL index entries?</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amconcurrent</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>does AM support concurrent updates?</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amgettuple</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry><quote>next valid tuple</quote> function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>aminsert</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry><quote>insert this tuple</quote> function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>ambeginscan</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry><quote>start new scan</quote> function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amrescan</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry><quote>restart this scan</quote> function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amendscan</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry><quote>end this scan</quote> function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>ammarkpos</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry><quote>mark current scan position</quote> function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amrestrpos</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry><quote>restore marked scan position</quote> function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>ambuild</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry><quote>build new index</quote> function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>ambulkdelete</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry>bulk-delete function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amcostestimate</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry>estimate cost of an indexscan</entry>
|
|
</row>
|
|
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
An index AM that supports multiple columns (has
|
|
<structfield>amcanmulticol</structfield> true) <emphasis>must</>
|
|
support indexing nulls in columns after the first, because the planner
|
|
will assume the index can be used for queries on just the first
|
|
column(s). For example, consider an index on (a,b) and a query
|
|
WHERE a = 4. The system will assume the index can be used to scan for
|
|
rows with a = 4, which is wrong if the index omits rows where b is null.
|
|
However it is okay to omit rows where the first indexed column is null.
|
|
(GiST currently does so.)
|
|
<structfield>amindexnulls</structfield> should be set true only if the
|
|
index AM indexes all rows, including arbitrary combinations of nulls.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-amop">
|
|
<title>pg_amop</title>
|
|
|
|
<para>
|
|
<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>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>amopclaid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_opclass.oid</entry>
|
|
<entry>the index opclass this entry is for</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amopstrategy</entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>operator strategy number</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amopreqcheck</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>index hit must be rechecked</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amopopr</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_operator.oid</entry>
|
|
<entry>the operator's pg_operator OID</entry>
|
|
</row>
|
|
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-amproc">
|
|
<title>pg_amproc</title>
|
|
|
|
<para>
|
|
<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>pg_amproc Columns</title>
|
|
|
|
<tgroup cols=4>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Type</entry>
|
|
<entry>References</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
|
|
<row>
|
|
<entry>amopclaid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_opclass.oid</entry>
|
|
<entry>the index opclass this entry is for</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amprocnum</entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>support procedure index</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>amproc</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry>OID of the proc</entry>
|
|
</row>
|
|
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-attrdef">
|
|
<title>pg_attrdef</title>
|
|
|
|
<para>
|
|
This catalog 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>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>adrelid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>The table this column belongs to</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>adnum</entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry>pg_attribute.attnum</entry>
|
|
<entry>The number of the column</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>adbin</entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>An internal representation of the column default value</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>adsrc</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>pg_attribute</title>
|
|
|
|
<para>
|
|
<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>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>attrelid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>The table this column belongs to</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>attname</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Column name</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>atttypid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_type.oid</entry>
|
|
<entry>The data type of this column</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>attstattarget</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 datatype-dependent.
|
|
For scalar datatypes, <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>attlen</entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
This is a copy of
|
|
<structname>pg_type</structname>.<structfield>typlen</structfield>
|
|
of this column's type.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>attnum</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>attndims</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>attcacheoff</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Always -1 in storage, but when loaded into a tuple descriptor
|
|
in memory this may be updated to cache the offset of the attribute
|
|
within the tuple.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>atttypmod</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 typmod.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>attbyval</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
A copy of
|
|
<structname>pg_type</structname>.<structfield>typbyval</structfield>
|
|
of this column's type
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>attstorage</entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Normally a copy of
|
|
<structname>pg_type</structname>.<structfield>typstorage</structfield>
|
|
of this column's type. For TOASTable datatypes, this can be altered
|
|
after column creation to control storage policy.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>attisset</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
If true, this attribute is a set. In that case, what is really
|
|
stored in the attribute is the OID of a tuple in the
|
|
<structname>pg_proc</structname> catalog. The
|
|
<structname>pg_proc</structname> tuple contains the query
|
|
string that defines this set - i.e., the query to run to get
|
|
the set. So the <structfield>atttypid</structfield> (see
|
|
above) refers to the type returned by this query, but the
|
|
actual length of this attribute is the length (size) of an
|
|
<type>oid</type>. --- At least this is the theory. All this
|
|
is probably quite broken these days.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>attalign</entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
A copy of
|
|
<structname>pg_type</structname>.<structfield>typalign</structfield>
|
|
of this column's type
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>attnotnull</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
This represents a NOT NULL constraint. It is possible to
|
|
change this field to enable or disable the constraint.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>atthasdef</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>attisdropped</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>attislocal</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>attinhcount</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>pg_cast</title>
|
|
|
|
<para>
|
|
<structname>pg_cast</structname> stores data type conversion paths,
|
|
both built-in paths and those defined with <command>CREATE CAST</command>.
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>castsource</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_type.oid</entry>
|
|
<entry>OID of the source data type</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>casttarget</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_type.oid</entry>
|
|
<entry>OID of the target data type</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>castfunc</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry>
|
|
The OID of the function to use to perform this cast. Zero is
|
|
stored if the data types are binary coercible (that is, no
|
|
run-time operation is needed to perform the cast).
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>castcontext</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</>, <literal>::</>, or function-call 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>
|
|
</sect1>
|
|
|
|
<sect1 id="catalog-pg-class">
|
|
<title>pg_class</title>
|
|
|
|
<para>
|
|
<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, 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
|
|
fields are meaningful for all relation types.
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>relname</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Name of the table, index, view, etc.</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>relnamespace</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_namespace.oid</entry>
|
|
<entry>
|
|
The OID of the namespace that contains this relation
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>reltype</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_type.oid</entry>
|
|
<entry>
|
|
The OID of the data type that corresponds to this table, if any
|
|
(zero for indexes, which have no pg_type entry)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>relowner</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry>pg_shadow.usesysid</entry>
|
|
<entry>Owner of the relation</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>relam</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_am.oid</entry>
|
|
<entry>If this is an index, the access method used (B-tree, hash, etc.)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>relfilenode</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>relpages</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>reltuples</entry>
|
|
<entry><type>float4</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Number of tuples 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>reltoastrelid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</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>reltoastidxid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>
|
|
For a TOAST table, the OID of its index. 0 if not a TOAST table.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>relhasindex</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 relhasindex if it finds the
|
|
table has no indexes.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>relisshared</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>relkind</entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
'r' = ordinary table, 'i' = index, 'S' = sequence, 'v' = view,
|
|
'c' = composite type, 's' = special, 't' = TOAST table
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>relnatts</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
|
|
<structname>pg_attribute</structname>.<structfield>attnum</structfield>.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>relchecks</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>reltriggers</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>relukeys</entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>unused (<emphasis>Not</emphasis> the number of unique keys)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>relfkeys</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>relrefs</entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>unused</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>relhasoids</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>relhaspkey</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
True if the table has (or once had) a primary key.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>relhasrules</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>Table has rules; see
|
|
<structname>pg_rewrite</structname> catalog
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>relhassubclass</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>At least one table inherits from this one</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>relacl</entry>
|
|
<entry><type>aclitem[]</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Access permissions. 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>pg_constraint</title>
|
|
|
|
<para>
|
|
This system catalog 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.) See under <command>CREATE
|
|
TABLE</command> for more information.
|
|
</para>
|
|
|
|
<note>
|
|
<para>
|
|
NOT NULL constraints are represented in the <structname>pg_attribute</>
|
|
catalog.
|
|
</para>
|
|
</note>
|
|
|
|
<para>
|
|
CHECK constraints on domains are stored here, too. Global ASSERTIONS
|
|
(a currently-unsupported SQL feature) may someday appear here as well.
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>conname</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Constraint name (not necessarily unique!)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>connamespace</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_namespace.oid</entry>
|
|
<entry>
|
|
The OID of the namespace that contains this constraint
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>contype</entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
'c' = check constraint,
|
|
'f' = foreign key constraint,
|
|
'p' = primary key constraint,
|
|
'u' = unique constraint
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>condeferrable</entry>
|
|
<entry><type>boolean</type></entry>
|
|
<entry></entry>
|
|
<entry>Is the constraint deferrable?</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>condeferred</entry>
|
|
<entry><type>boolean</type></entry>
|
|
<entry></entry>
|
|
<entry>Is the constraint deferred by default?</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>conrelid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>The table this constraint is on; 0 if not a table constraint</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>contypid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_type.oid</entry>
|
|
<entry>The domain this constraint is on; 0 if not a domain constraint</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>confrelid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>If a foreign key, the referenced table; else 0</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>confupdtype</entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>Foreign key update action code</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>confdeltype</entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>Foreign key deletion action code</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>confmatchtype</entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>Foreign key match type</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>conkey</entry>
|
|
<entry><type>int2[]</type></entry>
|
|
<entry>pg_attribute.attnum</entry>
|
|
<entry>If a table constraint, list of columns which the constraint constrains</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>confkey</entry>
|
|
<entry><type>int2[]</type></entry>
|
|
<entry>pg_attribute.attnum</entry>
|
|
<entry>If a foreign key, list of the referenced columns</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>conbin</entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>If a check constraint, an internal representation of the expression</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>consrc</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>
|
|
<structname>pg_class</structname>.<structfield>relchecks</structfield>
|
|
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>pg_conversion</title>
|
|
|
|
<para>
|
|
This system catalog stores encoding conversion information. See
|
|
<command>CREATE CONVERSION</command> for more information.
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>conname</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Conversion name (unique within a namespace)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>connamespace</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_namespace.oid</entry>
|
|
<entry>
|
|
The OID of the namespace that contains this conversion
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>conowner</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry>pg_shadow.usesysid</entry>
|
|
<entry>Owner (creator) of the namespace</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>conforencoding</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>Source(for) encoding ID</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>contoencoding</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>Destination(to) encoding ID</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>conproc</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry>Conversion procedure</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>condefault</entry>
|
|
<entry><type>boolean</type></entry>
|
|
<entry></entry>
|
|
<entry>true if this is the default conversion</entry>
|
|
</row>
|
|
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="catalog-pg-database">
|
|
<title>pg_database</title>
|
|
|
|
<para>
|
|
The <structname>pg_database</structname> catalog stores information
|
|
about the available databases. Databases are created with the
|
|
<command>CREATE DATABASE</command> command. Consult the
|
|
&cite-admin; 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>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>datname</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Database name</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>datdba</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry>pg_shadow.usesysid</entry>
|
|
<entry>Owner of the database, usually the user who created it</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>encoding</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>Character/multibyte encoding for this database</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>datistemplate</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
If true then this database can be used in the
|
|
<quote>TEMPLATE</quote> clause of <command>CREATE
|
|
DATABASE</command> to create a new database as a clone of
|
|
this one.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>datallowconn</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 template0 database from being altered.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>datlastsysoid</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>datvacuumxid</entry>
|
|
<entry><type>xid</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
All tuples 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>datfrozenxid</entry>
|
|
<entry><type>xid</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
All tuples 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 wraparound problems.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>datpath</entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
If the database is stored at an alternative location then this
|
|
records the location. It's either an environment variable name
|
|
or an absolute path, depending how it was entered.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>datconfig</entry>
|
|
<entry><type>text[]</type></entry>
|
|
<entry></entry>
|
|
<entry>Session defaults for run-time configuration variables</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>datacl</entry>
|
|
<entry><type>aclitem[]</type></entry>
|
|
<entry></entry>
|
|
<entry>Access permissions</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-depend">
|
|
<title>pg_depend</title>
|
|
|
|
<para>
|
|
The <structname>pg_depend</structname> table 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>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>classid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>The oid of the system catalog the dependent object is in</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>objid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>any oid attribute</entry>
|
|
<entry>The oid of the specific dependent object</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>objsubid</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>For a table attribute, this is the attribute's
|
|
column number (the objid and classid refer to the table itself).
|
|
For all other object types, this field is presently zero.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>refclassid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>The oid of the system catalog the referenced object is in</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>refobjid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>any oid attribute</entry>
|
|
<entry>The oid of the specific referenced object</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>refobjsubid</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>For a table attribute, this is the attribute's
|
|
column number (the refobjid and refclassid refer to the table itself).
|
|
For all other object types, this field is presently zero.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>deptype</entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
A code defining the specific semantics of this dependency relationship.
|
|
</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</>:
|
|
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para>
|
|
DEPENDENCY_NORMAL ('n'): 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 CASCADE, in which case the dependent object is dropped too.
|
|
Example: a table column has a normal dependency on its datatype.
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>
|
|
DEPENDENCY_AUTO ('a'): the dependent object can be dropped separately
|
|
from the referenced object, and should be automatically dropped
|
|
(regardless of RESTRICT or CASCADE mode) if the referenced object
|
|
is dropped.
|
|
Example: a named constraint on a table is made auto-dependent on
|
|
the table, so that it will go away if the table is dropped.
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>
|
|
DEPENDENCY_INTERNAL ('i'): the dependent object was created as part
|
|
of creation of the referenced object, and is really just a part of
|
|
its internal implementation. A DROP of the dependent object will be
|
|
disallowed outright (we'll tell the user to issue a DROP against the
|
|
referenced object, instead). A DROP of the referenced object will be
|
|
propagated through to drop the dependent object whether 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 pg_constraint entry.
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>
|
|
DEPENDENCY_PIN ('p'): 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 during initdb. The fields for the dependent object
|
|
contain zeroes.
|
|
</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
|
|
Other dependency flavors may be needed in future.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-description">
|
|
<title>pg_description</title>
|
|
|
|
<para>
|
|
The pg_description table 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 pg_description.
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>objoid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>any oid attribute</entry>
|
|
<entry>The oid of the object this description pertains to</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>classoid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>The oid of the system catalog this object appears in</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>objsubid</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>For a comment on a table attribute, this is the attribute's
|
|
column number (the objoid and classoid refer to the table itself).
|
|
For all other object types, this field is presently zero.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>description</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>pg_group</title>
|
|
|
|
<para>
|
|
This catalog defines groups and stores what users belong to what
|
|
groups. Groups are created with the <command>CREATE
|
|
GROUP</command> command. Consult the &cite-admin; for information
|
|
about user permission 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>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>groname</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Name of the group</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>grosysid</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>An arbitrary number to identify this group</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>grolist</entry>
|
|
<entry><type>int4[]</type></entry>
|
|
<entry>pg_shadow.usesysid</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>pg_index</title>
|
|
|
|
<para>
|
|
<structname>pg_index</structname> contains part of the information
|
|
about indexes. The rest is mostly in
|
|
<structname>pg_class</structname>.
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>indexrelid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>The OID of the pg_class entry for this index</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>indrelid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>The OID of the pg_class entry for the table this index is for</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>indproc</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry>The function's OID if this is a functional index,
|
|
else zero</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>indkey</entry>
|
|
<entry><type>int2vector</type></entry>
|
|
<entry>pg_attribute.attnum</entry>
|
|
<entry>
|
|
This is a vector (array) of up to
|
|
<symbol>INDEX_MAX_KEYS</symbol> values that indicate which
|
|
table columns this index pertains to. For example a value of
|
|
<literal>1 3</literal> would mean that the first and the third
|
|
column make up the index key. For a functional index, these
|
|
columns are the inputs to the function, and the function's return
|
|
value is the index key.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>indclass</entry>
|
|
<entry><type>oidvector</type></entry>
|
|
<entry>pg_opclass.oid</entry>
|
|
<entry>
|
|
For each column in the index key this contains a reference to
|
|
the <quote>operator class</quote> to use. See
|
|
<structname>pg_opclass</structname> for details.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>indisclustered</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>If true, the table was last clustered on this index.</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>indisunique</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>If true, this is a unique index.</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>indisprimary</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>If true, this index represents the primary key of the table.
|
|
(indisunique should always be true when this is true.)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>indreference</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry></entry>
|
|
<entry>unused</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>indpred</entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>Expression tree (in the form of a nodeToString representation)
|
|
for partial index predicate. Empty string if not a partial
|
|
index.</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-inherits">
|
|
<title>pg_inherits</title>
|
|
|
|
<para>
|
|
This catalog records information about table inheritance hierarchies.
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>inhrelid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>
|
|
The OID of the child table.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>inhparent</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>
|
|
The OID of the parent table.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>inhseqno</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>pg_language</title>
|
|
|
|
<para>
|
|
<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 the
|
|
&cite-programmer; for more information about language handlers.
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>lanname</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Name of the language (to be specified when creating a function)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>lanispl</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>lanpltrusted</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 field is meaningless.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>lanplcallfoid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry>
|
|
For non-internal 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>lanvalidator</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_proc.oid</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>lanacl</entry>
|
|
<entry><type>aclitem[]</type></entry>
|
|
<entry></entry>
|
|
<entry>Access permissions</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-largeobject">
|
|
<title>pg_largeobject</title>
|
|
|
|
<para>
|
|
<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 LOBLKSIZE (which is currently
|
|
BLCKSZ/4, or typically 2Kbytes).
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>loid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry></entry>
|
|
<entry>Identifier of the large object that includes this page</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>pageno</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>data</entry>
|
|
<entry><type>bytea</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
Actual data stored in the large object.
|
|
This will never be more than 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 (pageno * LOBLKSIZE) within the object. The implementation
|
|
allows sparse storage: pages may be missing, and may be shorter than
|
|
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>pg_listener</title>
|
|
|
|
<para>
|
|
<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>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>relname</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Notify condition name. (The name need not match any actual
|
|
relation in the database; the term <quote>relname</> is historical.)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>listenerpid</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>PID of the backend process that created this entry.</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>notification</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 backend that sent the notification.
|
|
</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-namespace">
|
|
<title>pg_namespace</title>
|
|
|
|
<para>
|
|
A namespace is the structure underlying SQL92 schemas: each namespace
|
|
can have a separate collection of relations, types, etc without name
|
|
conflicts.
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>nspname</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Name of the namespace</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>nspowner</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry>pg_shadow.usesysid</entry>
|
|
<entry>Owner (creator) of the namespace</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>nspacl</entry>
|
|
<entry><type>aclitem[]</type></entry>
|
|
<entry></entry>
|
|
<entry>Access permissions</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-opclass">
|
|
<title>pg_opclass</title>
|
|
|
|
<para>
|
|
<structname>pg_opclass</structname> defines
|
|
index access method operator classes. Each operator class defines
|
|
semantics for index columns of a particular datatype and a particular
|
|
index access method. Note that there can be multiple operator classes
|
|
for a given datatype/access method combination, thus supporting multiple
|
|
behaviors.
|
|
</para>
|
|
|
|
<para>
|
|
Operator classes are described at length in the &cite-programmer;.
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>opcamid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_am.oid</entry>
|
|
<entry>index access method opclass is for</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>opcname</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>name of this opclass</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>opcnamespace</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_namespace.oid</entry>
|
|
<entry>namespace of this opclass</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>opcowner</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry>pg_shadow.usesysid</entry>
|
|
<entry>opclass owner</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>opcintype</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_type.oid</entry>
|
|
<entry>type of input data for opclass</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>opcdefault</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>true if opclass is default for opcintype</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>opckeytype</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_type.oid</entry>
|
|
<entry>type of index data, or zero if same as 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>pg_operator</title>
|
|
|
|
<para>
|
|
See <command>CREATE OPERATOR</command> and the &cite-programmer;
|
|
for details on these operator parameters.
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>oprname</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Name of the operator</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>oprnamespace</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_namespace.oid</entry>
|
|
<entry>
|
|
The OID of the namespace that contains this operator
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>oprowner</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry>pg_shadow.usesysid</entry>
|
|
<entry>Owner (creator) of the operator</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>oprkind</entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
'b' = infix (<quote>both</quote>), 'l' = prefix
|
|
(<quote>left</quote>), 'r' = postfix (<quote>right</quote>)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>oprcanhash</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>This operator supports hash joins.</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>oprleft</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_type.oid</entry>
|
|
<entry>Type of the left operand</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>oprright</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_type.oid</entry>
|
|
<entry>Type of the right operand</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>oprresult</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_type.oid</entry>
|
|
<entry>Type of the result</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>oprcom</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_operator.oid</entry>
|
|
<entry>Commutator of this operator, if any</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>oprnegate</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_operator.oid</entry>
|
|
<entry>Negator of this operator, if any</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>oprlsortop</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_operator.oid</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>oprrsortop</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_operator.oid</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>oprltcmpop</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_operator.oid</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>oprgtcmpop</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_operator.oid</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>oprcode</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry>Function that implements this operator</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>oprrest</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry>Restriction selectivity estimation function for this operator</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>oprjoin</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry>Join selectivity estimation function for this operator</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
Unused fields contain zeroes, for example oprleft is zero for a
|
|
prefix operator.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-proc">
|
|
<title>pg_proc</title>
|
|
|
|
<para>
|
|
This catalog stores information about functions (or procedures).
|
|
The description of <command>CREATE FUNCTION</command> and the
|
|
&cite-programmer; contain more information about the meaning of
|
|
some fields.
|
|
</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 <structname>pg_aggregate</structname>.
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>proname</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Name of the function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>pronamespace</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_namespace.oid</entry>
|
|
<entry>
|
|
The OID of the namespace that contains this function
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>proowner</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry>pg_shadow.usesysid</entry>
|
|
<entry>Owner (creator) of the function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>prolang</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_language.oid</entry>
|
|
<entry>Implementation language or call interface of this function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>proisagg</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>Function is an aggregate function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>prosecdef</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>Function is a security definer (i.e., a <quote>setuid</>
|
|
function)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>proisstrict</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>proretset</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>Function returns a set (ie, multiple values of the specified
|
|
data type)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>provolatile</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>pronargs</entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>Number of arguments</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>prorettype</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_type.oid</entry>
|
|
<entry>Data type of the return value</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>proargtypes</entry>
|
|
<entry><type>oidvector</type></entry>
|
|
<entry>pg_type.oid</entry>
|
|
<entry>A vector with the data types of the function arguments</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>prosrc</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>probin</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>proacl</entry>
|
|
<entry><type>aclitem[]</type></entry>
|
|
<entry></entry>
|
|
<entry>Access permissions</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
Currently, prosrc contains the function's C-language name (link symbol)
|
|
for compiled functions, both built-in and dynamically loaded. For all
|
|
other language types, prosrc contains the function's source text.
|
|
</para>
|
|
|
|
<para>
|
|
Currently, probin 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>pg_rewrite</title>
|
|
|
|
<para>
|
|
This system catalog stores rewrite rules for tables and views.
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>rulename</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Rule name</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>ev_class</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>The table this rule is for</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>ev_attr</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>ev_type</entry>
|
|
<entry><type>char</type></entry>
|
|
<entry></entry>
|
|
<entry>Event type that the rule is for: '1' = SELECT,
|
|
'2' = UPDATE, '3' = INSERT, '4' = DELETE</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>is_instead</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>True if the rule is an INSTEAD rule</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>ev_qual</entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>Expression tree (in the form of a nodeToString representation)
|
|
for the rule's qualifying condition</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>ev_action</entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>Query tree (in the form of a nodeToString representation)
|
|
for the rule's action</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<note>
|
|
<para>
|
|
<structname>pg_class</structname>.<structfield>relhasrules</structfield>
|
|
must be true if a table has any rules in this catalog.
|
|
</para>
|
|
</note>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-shadow">
|
|
<title>pg_shadow</title>
|
|
|
|
<para>
|
|
<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.
|
|
<structname>pg_user</structname> is a publicly readable view on
|
|
<structname>pg_shadow</structname> that blanks out the password field.
|
|
</para>
|
|
|
|
<para>
|
|
The &cite-admin; contains detailed information about user and
|
|
permission 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>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>usename</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>User name</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>usesysid</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>User id (arbitrary number used to reference this user)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>usecreatedb</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>User may create databases</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>usesuper</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>User is a superuser</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>usecatupd</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>
|
|
User may update system catalogs. (Even a superuser may not do
|
|
this unless this attribute is true.)
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>passwd</entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry>Password</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>valuntil</entry>
|
|
<entry><type>abstime</type></entry>
|
|
<entry></entry>
|
|
<entry>Account expiry time (only used for password authentication)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>useconfig</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>pg_statistic</title>
|
|
|
|
<para>
|
|
<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>
|
|
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 NULL-ness) 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.)
|
|
<structname>pg_stats</structname> is a publicly readable view on
|
|
<structname>pg_statistic</structname> that only exposes information
|
|
about those tables that are readable by the current user.
|
|
<structname>pg_stats</structname> is also designed to present the
|
|
information in a more readable format than the underlying
|
|
<structname>pg_statistic</structname> table --- at the cost that
|
|
its schema must be extended whenever new slot types are added.
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>starelid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>The table that the described column belongs to</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>staattnum</entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry>pg_attribute.attnum</entry>
|
|
<entry>The number of the described column</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>stanullfrac</entry>
|
|
<entry><type>float4</type></entry>
|
|
<entry></entry>
|
|
<entry>The fraction of the column's entries that are NULL</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>stawidth</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry>The average stored width, in bytes, of non-NULL entries</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>stadistinct</entry>
|
|
<entry><type>float4</type></entry>
|
|
<entry></entry>
|
|
<entry>The number of distinct non-NULL 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 stadistinct = -0.5).
|
|
A zero value means the number of distinct values is unknown.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>stakindN</entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>A code number indicating the kind of statistics stored in the Nth
|
|
<quote>slot</quote> of the <structname>pg_statistic</structname> row.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>staopN</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_operator.oid</entry>
|
|
<entry>An operator used to derive the statistics stored in the
|
|
Nth <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>stanumbersN</entry>
|
|
<entry><type>float4[]</type></entry>
|
|
<entry></entry>
|
|
<entry>Numerical statistics of the appropriate kind for the Nth
|
|
<quote>slot</quote>, or NULL if the slot kind does not involve numerical values.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>stavaluesN</entry>
|
|
<entry><type>text[]</type></entry>
|
|
<entry></entry>
|
|
<entry>Column data values of the appropriate kind for the Nth
|
|
<quote>slot</quote>, or NULL if the slot kind does not store any data values.
|
|
For data-type independence, all column data values are converted
|
|
to external textual form and stored as TEXT datums.
|
|
</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-trigger">
|
|
<title>pg_trigger</title>
|
|
|
|
<para>
|
|
This system catalog stores triggers on tables. See under
|
|
<command>CREATE TRIGGER</command> for more information.
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>tgrelid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>The table this trigger is on</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>tgname</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Trigger name (must be unique among triggers of same table)</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>tgfoid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry>The function to be called</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>tgtype</entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>Bitmask identifying trigger conditions</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>tgenabled</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>tgisconstraint</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>True if trigger implements an RI constraint</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>tgconstrname</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>RI constraint name</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>tgconstrrelid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>The table referenced by an RI constraint</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>tgdeferrable</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>True if deferrable</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>tginitdeferred</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry>True if initially deferred</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>tgnargs</entry>
|
|
<entry><type>int2</type></entry>
|
|
<entry></entry>
|
|
<entry>Number of argument strings passed to trigger function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>tgattr</entry>
|
|
<entry><type>int2vector</type></entry>
|
|
<entry></entry>
|
|
<entry>Currently unused</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>tgargs</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>
|
|
<structname>pg_class</structname>.<structfield>reltriggers</structfield>
|
|
needs to match up with the entries in this table.
|
|
</para>
|
|
</note>
|
|
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="catalog-pg-type">
|
|
<title>pg_type</title>
|
|
|
|
<para>
|
|
This catalog stores information about data types. Scalar types
|
|
(<quote>base types</>) are created with <command>CREATE TYPE</command>.
|
|
A complex type is automatically created for each table in the database, to
|
|
represent the row structure of the table. It is also possible to create
|
|
complex types with <command>CREATE TYPE AS</command>, and
|
|
derived types with <command>CREATE DOMAIN</command>.
|
|
</para>
|
|
|
|
<table>
|
|
<title>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>typname</entry>
|
|
<entry><type>name</type></entry>
|
|
<entry></entry>
|
|
<entry>Data type name</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>typnamespace</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_namespace.oid</entry>
|
|
<entry>
|
|
The OID of the namespace that contains this type
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>typowner</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry>pg_shadow.usesysid</entry>
|
|
<entry>Owner (creator) of the type</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>typlen</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>typbyval</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.
|
|
Only <type>char</type>, <type>short</type>, and
|
|
<type>int</type> equivalent items can be passed by value, so if
|
|
the type is not 1, 2, or 4 bytes long,
|
|
<productname>PostgreSQL</> does not have
|
|
the option of passing by value and so
|
|
<structfield>typbyval</structfield> had better be false.
|
|
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>typtype</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 complex type (i.e.,
|
|
a table's row type), <literal>d</literal> for a derived type (i.e.,
|
|
a domain), or <literal>p</literal> for a pseudo-type. See also
|
|
<structfield>typrelid</structfield>
|
|
and <structfield>typbasetype</structfield>.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>typisdefined</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 typisdefined is false,
|
|
nothing except the type name, namespace, and OID can be relied on.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>typdelim</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>typrelid</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_class.oid</entry>
|
|
<entry>
|
|
If this is a complex type (see
|
|
<structfield>typtype</structfield>), then this field 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-complex types.
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>typelem</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_type.oid</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 N 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>typinput</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry>Input conversion function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>typoutput</entry>
|
|
<entry><type>regproc</type></entry>
|
|
<entry>pg_proc.oid</entry>
|
|
<entry>Output conversion function</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>typalign</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>'c' = CHAR alignment, i.e., no alignment needed.</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>'s' = SHORT alignment (2 bytes on most machines).</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>'i' = INT alignment (4 bytes on most machines).</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>'d' = DOUBLE 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 field in
|
|
a struct representing a table row.
|
|
</para>
|
|
</note></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>typstorage</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>'p': Value must always be stored plain.</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
'e': Value can be stored in a <quote>secondary</quote>
|
|
relation (if relation has one, see
|
|
<structname>pg_class</structname>.<structfield>reltoastrelid</structfield>).
|
|
</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>'m': Value can be stored compressed inline.</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>'x': Value can be stored compressed inline or in <quote>secondary</quote>.</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
Note that 'm' fields can also be moved out to secondary
|
|
storage, but only as a last resort ('e' and 'x' fields are
|
|
moved first).
|
|
</para></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>typnotnull</entry>
|
|
<entry><type>bool</type></entry>
|
|
<entry></entry>
|
|
<entry><para>
|
|
<structfield>typnotnull</structfield> represents a NOT NULL
|
|
constraint on a type. Presently used for domains only.
|
|
</para></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>typbasetype</entry>
|
|
<entry><type>oid</type></entry>
|
|
<entry>pg_type.oid</entry>
|
|
<entry><para>
|
|
If this is a derived type (see <structfield>typtype</structfield>),
|
|
then <structfield>typbasetype</structfield> identifies
|
|
the type that this one is based on. Zero if not a derived type.
|
|
</para></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>typtypmod</entry>
|
|
<entry><type>int4</type></entry>
|
|
<entry></entry>
|
|
<entry><para>
|
|
Domains use <structfield>typtypmod</structfield> to record the typmod
|
|
to be applied to their base type (-1 if base type does not use a
|
|
typmod). -1 if this type is not a domain.
|
|
</para></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>typndims</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, typbasetype is an array type;
|
|
the domain's typelem will match the base type's typelem).
|
|
Zero for non-domains and non-array domains.
|
|
</para></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>typdefaultbin</entry>
|
|
<entry><type>text</type></entry>
|
|
<entry></entry>
|
|
<entry><para>
|
|
If <structfield>typdefaultbin</> is not NULL, it is the nodeToString
|
|
representation of a default expression for the type. Currently this is
|
|
only used for domains.
|
|
</para></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>typdefault</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>
|
|
</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:
|
|
-->
|