241 lines
8.4 KiB
C
241 lines
8.4 KiB
C
/*-------------------------------------------------------------------------
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*
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* pg_attribute.h
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* definition of the "attribute" system catalog (pg_attribute)
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*
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* The initial contents of pg_attribute are generated at compile time by
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* genbki.pl, so there is no pg_attribute.dat file. Only "bootstrapped"
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* relations need be included.
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*
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*
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* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/catalog/pg_attribute.h
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*
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* NOTES
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* The Catalog.pm module reads this file and derives schema
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* information.
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PG_ATTRIBUTE_H
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#define PG_ATTRIBUTE_H
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#include "catalog/genbki.h"
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#include "catalog/pg_attribute_d.h"
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/* ----------------
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* pg_attribute definition. cpp turns this into
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* typedef struct FormData_pg_attribute
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*
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* If you change the following, make sure you change the structs for
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* system attributes in catalog/heap.c also.
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* You may need to change catalog/genbki.pl as well.
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* ----------------
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*/
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CATALOG(pg_attribute,1249,AttributeRelationId) BKI_BOOTSTRAP BKI_ROWTYPE_OID(75,AttributeRelation_Rowtype_Id) BKI_SCHEMA_MACRO
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{
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Oid attrelid BKI_LOOKUP(pg_class); /* OID of relation containing
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* this attribute */
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NameData attname; /* name of attribute */
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/*
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* atttypid is the OID of the instance in Catalog Class pg_type that
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* defines the data type of this attribute (e.g. int4). Information in
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* that instance is redundant with the attlen, attbyval, and attalign
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* attributes of this instance, so they had better match or Postgres will
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* fail. In an entry for a dropped column, this field is set to zero
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* since the pg_type entry may no longer exist; but we rely on attlen,
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* attbyval, and attalign to still tell us how large the values in the
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* table are.
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*/
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Oid atttypid BKI_LOOKUP_OPT(pg_type);
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/*
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* attlen is a copy of the typlen field from pg_type for this attribute.
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* See atttypid comments above.
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*/
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int16 attlen;
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/*
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* attnum is the "attribute number" for the attribute: A value that
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* uniquely identifies this attribute within its class. For user
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* attributes, Attribute numbers are greater than 0 and not greater than
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* the number of attributes in the class. I.e. if the Class pg_class says
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* that Class XYZ has 10 attributes, then the user attribute numbers in
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* Class pg_attribute must be 1-10.
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*
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* System attributes have attribute numbers less than 0 that are unique
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* within the class, but not constrained to any particular range.
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*
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* Note that (attnum - 1) is often used as the index to an array.
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*/
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int16 attnum;
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/*
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* fastgetattr() uses attcacheoff to cache byte offsets of attributes in
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* heap tuples. The value actually stored in pg_attribute (-1) indicates
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* no cached value. But when we copy these tuples into a tuple
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* descriptor, we may then update attcacheoff in the copies. This speeds
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* up the attribute walking process.
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*/
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int32 attcacheoff BKI_DEFAULT(-1);
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/*
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* atttypmod records type-specific data supplied at table creation time
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* (for example, the max length of a varchar field). It is passed to
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* type-specific input and output functions as the third argument. The
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* value will generally be -1 for types that do not need typmod.
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*/
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int32 atttypmod BKI_DEFAULT(-1);
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/*
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* attndims is the declared number of dimensions, if an array type,
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* otherwise zero.
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*/
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int16 attndims;
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/*
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* attbyval is a copy of the typbyval field from pg_type for this
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* attribute. See atttypid comments above.
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*/
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bool attbyval;
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/*
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* attalign is a copy of the typalign field from pg_type for this
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* attribute. See atttypid comments above.
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*/
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char attalign;
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/*----------
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* attstorage tells for VARLENA attributes, what the heap access
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* methods can do to it if a given tuple doesn't fit into a page.
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* Possible values are as for pg_type.typstorage (see TYPSTORAGE macros).
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*----------
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*/
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char attstorage;
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/*
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* attcompression sets the current compression method of the attribute.
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* Typically this is InvalidCompressionMethod ('\0') to specify use of the
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* current default setting (see default_toast_compression). Otherwise,
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* 'p' selects pglz compression, while 'l' selects LZ4 compression.
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* However, this field is ignored whenever attstorage does not allow
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* compression.
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*/
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char attcompression BKI_DEFAULT('\0');
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/* This flag represents the "NOT NULL" constraint */
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bool attnotnull;
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/* Has DEFAULT value or not */
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bool atthasdef BKI_DEFAULT(f);
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/* Has a missing value or not */
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bool atthasmissing BKI_DEFAULT(f);
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/* One of the ATTRIBUTE_IDENTITY_* constants below, or '\0' */
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char attidentity BKI_DEFAULT('\0');
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/* One of the ATTRIBUTE_GENERATED_* constants below, or '\0' */
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char attgenerated BKI_DEFAULT('\0');
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/* Is dropped (ie, logically invisible) or not */
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bool attisdropped BKI_DEFAULT(f);
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/*
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* This flag specifies whether this column has ever had a local
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* definition. It is set for normal non-inherited columns, but also for
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* columns that are inherited from parents if also explicitly listed in
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* CREATE TABLE INHERITS. It is also set when inheritance is removed from
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* a table with ALTER TABLE NO INHERIT. If the flag is set, the column is
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* not dropped by a parent's DROP COLUMN even if this causes the column's
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* attinhcount to become zero.
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*/
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bool attislocal BKI_DEFAULT(t);
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/* Number of times inherited from direct parent relation(s) */
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int16 attinhcount BKI_DEFAULT(0);
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/* attribute's collation, if any */
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Oid attcollation BKI_LOOKUP_OPT(pg_collation);
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#ifdef CATALOG_VARLEN /* variable-length/nullable fields start here */
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/* NOTE: The following fields are not present in tuple descriptors. */
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/*
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* attstattarget is the target number of statistics datapoints to collect
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* during VACUUM ANALYZE of this column. A zero here indicates that we do
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* not wish to collect any stats about this column. A null value here
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* indicates that no value has been explicitly set for this column, so
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* ANALYZE should use the default setting.
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*
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* int16 is sufficient for the current max value (MAX_STATISTICS_TARGET).
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*/
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int16 attstattarget BKI_DEFAULT(_null_) BKI_FORCE_NULL;
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/* Column-level access permissions */
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aclitem attacl[1] BKI_DEFAULT(_null_);
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/* Column-level options */
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text attoptions[1] BKI_DEFAULT(_null_);
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/* Column-level FDW options */
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text attfdwoptions[1] BKI_DEFAULT(_null_);
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/*
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* Missing value for added columns. This is a one element array which lets
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* us store a value of the attribute type here.
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*/
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anyarray attmissingval BKI_DEFAULT(_null_);
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#endif
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} FormData_pg_attribute;
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/*
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* ATTRIBUTE_FIXED_PART_SIZE is the size of the fixed-layout,
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* guaranteed-not-null part of a pg_attribute row. This is in fact as much
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* of the row as gets copied into tuple descriptors, so don't expect you
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* can access the variable-length fields except in a real tuple!
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*/
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#define ATTRIBUTE_FIXED_PART_SIZE \
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(offsetof(FormData_pg_attribute,attcollation) + sizeof(Oid))
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/* ----------------
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* Form_pg_attribute corresponds to a pointer to a tuple with
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* the format of pg_attribute relation.
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* ----------------
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*/
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typedef FormData_pg_attribute *Form_pg_attribute;
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/*
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* FormExtraData_pg_attribute contains (some of) the fields that are not in
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* FormData_pg_attribute because they are excluded by CATALOG_VARLEN. It is
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* meant to be used by DDL code so that the combination of
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* FormData_pg_attribute (often via tuple descriptor) and
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* FormExtraData_pg_attribute can be used to pass around all the information
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* about an attribute. Fields can be included here as needed.
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*/
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typedef struct FormExtraData_pg_attribute
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{
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NullableDatum attstattarget;
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NullableDatum attoptions;
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} FormExtraData_pg_attribute;
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DECLARE_UNIQUE_INDEX(pg_attribute_relid_attnam_index, 2658, AttributeRelidNameIndexId, pg_attribute, btree(attrelid oid_ops, attname name_ops));
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DECLARE_UNIQUE_INDEX_PKEY(pg_attribute_relid_attnum_index, 2659, AttributeRelidNumIndexId, pg_attribute, btree(attrelid oid_ops, attnum int2_ops));
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MAKE_SYSCACHE(ATTNAME, pg_attribute_relid_attnam_index, 32);
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MAKE_SYSCACHE(ATTNUM, pg_attribute_relid_attnum_index, 128);
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#ifdef EXPOSE_TO_CLIENT_CODE
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#define ATTRIBUTE_IDENTITY_ALWAYS 'a'
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#define ATTRIBUTE_IDENTITY_BY_DEFAULT 'd'
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#define ATTRIBUTE_GENERATED_STORED 's'
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#endif /* EXPOSE_TO_CLIENT_CODE */
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#endif /* PG_ATTRIBUTE_H */
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