pg_attribute.h

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/*-------------------------------------------------------------------------
 *
 * pg_attribute.h
 *    definition of the "attribute" system catalog (pg_attribute)
 *
 * The initial contents of pg_attribute are generated at compile time by
 * genbki.pl, so there is no pg_attribute.dat file.  Only "bootstrapped"
 * relations need be included.
 *
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/catalog/pg_attribute.h
 *
 * NOTES
 *    The Catalog.pm module reads this file and derives schema
 *    information.
 *
 *-------------------------------------------------------------------------
 */
#ifndef PG_ATTRIBUTE_H
#define PG_ATTRIBUTE_H
 
#include "catalog/genbki.h"
#include "catalog/pg_attribute_d.h" /* IWYU pragma: export */
 
/* ----------------
 *      pg_attribute definition.  cpp turns this into
 *      typedef struct FormData_pg_attribute
 *
 *      If you change the following, make sure you change the structs for
 *      system attributes in catalog/heap.c also.
 *      You may need to change catalog/genbki.pl as well.
 * ----------------
 */
CATALOG(pg_attribute,1249,AttributeRelationId) BKI_BOOTSTRAP BKI_ROWTYPE_OID(75,AttributeRelation_Rowtype_Id) BKI_SCHEMA_MACRO
{
    Oid         attrelid BKI_LOOKUP(pg_class);  /* OID of relation containing
                                                 * this attribute */
    NameData    attname;        /* name of attribute */
 
    /*
     * atttypid is the OID of the instance in Catalog Class pg_type that
     * defines the data type of this attribute (e.g. int4).  Information in
     * that instance is redundant with the attlen, attbyval, and attalign
     * attributes of this instance, so they had better match or Postgres will
     * fail.  In an entry for a dropped column, this field is set to zero
     * since the pg_type entry may no longer exist; but we rely on attlen,
     * attbyval, and attalign to still tell us how large the values in the
     * table are.
     */
    Oid         atttypid BKI_LOOKUP_OPT(pg_type);
 
    /*
     * attlen is a copy of the typlen field from pg_type for this attribute.
     * See atttypid comments above.
     */
    int16       attlen;
 
    /*
     * attnum is the "attribute number" for the attribute:  A value that
     * uniquely identifies this attribute within its class. For user
     * attributes, Attribute numbers are greater than 0 and not greater than
     * the number of attributes in the class. I.e. if the Class pg_class says
     * that Class XYZ has 10 attributes, then the user attribute numbers in
     * Class pg_attribute must be 1-10.
     *
     * System attributes have attribute numbers less than 0 that are unique
     * within the class, but not constrained to any particular range.
     *
     * Note that (attnum - 1) is often used as the index to an array.
     */
    int16       attnum;
 
    /*
     * atttypmod records type-specific data supplied at table creation time
     * (for example, the max length of a varchar field).  It is passed to
     * type-specific input and output functions as the third argument. The
     * value will generally be -1 for types that do not need typmod.
     */
    int32       atttypmod BKI_DEFAULT(-1);
 
    /*
     * attndims is the declared number of dimensions, if an array type,
     * otherwise zero.
     */
    int16       attndims;
 
    /*
     * attbyval is a copy of the typbyval field from pg_type for this
     * attribute.  See atttypid comments above.
     */
    bool        attbyval;
 
    /*
     * attalign is a copy of the typalign field from pg_type for this
     * attribute.  See atttypid comments above.
     */
    char        attalign;
 
    /*----------
     * attstorage tells for VARLENA attributes, what the heap access
     * methods can do to it if a given tuple doesn't fit into a page.
     * Possible values are as for pg_type.typstorage (see TYPSTORAGE macros).
     *----------
     */
    char        attstorage;
 
    /*
     * attcompression sets the current compression method of the attribute.
     * Typically this is InvalidCompressionMethod ('\0') to specify use of the
     * current default setting (see default_toast_compression).  Otherwise,
     * 'p' selects pglz compression, while 'l' selects LZ4 compression.
     * However, this field is ignored whenever attstorage does not allow
     * compression.
     */
    char        attcompression BKI_DEFAULT('\0');
 
    /*
     * Whether a (possibly invalid) not-null constraint exists for the column
     */
    bool        attnotnull;
 
    /* Has DEFAULT value or not */
    bool        atthasdef BKI_DEFAULT(f);
 
    /* Has a missing value or not */
    bool        atthasmissing BKI_DEFAULT(f);
 
    /* One of the ATTRIBUTE_IDENTITY_* constants below, or '\0' */
    char        attidentity BKI_DEFAULT('\0');
 
    /* One of the ATTRIBUTE_GENERATED_* constants below, or '\0' */
    char        attgenerated BKI_DEFAULT('\0');
 
    /* Is dropped (ie, logically invisible) or not */
    bool        attisdropped BKI_DEFAULT(f);
 
    /*
     * This flag specifies whether this column has ever had a local
     * definition.  It is set for normal non-inherited columns, but also for
     * columns that are inherited from parents if also explicitly listed in
     * CREATE TABLE INHERITS.  It is also set when inheritance is removed from
     * a table with ALTER TABLE NO INHERIT.  If the flag is set, the column is
     * not dropped by a parent's DROP COLUMN even if this causes the column's
     * attinhcount to become zero.
     */
    bool        attislocal BKI_DEFAULT(t);
 
    /* Number of times inherited from direct parent relation(s) */
    int16       attinhcount BKI_DEFAULT(0);
 
    /* attribute's collation, if any */
    Oid         attcollation BKI_LOOKUP_OPT(pg_collation);
 
#ifdef CATALOG_VARLEN           /* variable-length/nullable fields start here */
    /* NOTE: The following fields are not present in tuple descriptors. */
 
    /*
     * attstattarget is the target number of statistics datapoints to collect
     * during VACUUM ANALYZE of this column.  A zero here indicates that we do
     * not wish to collect any stats about this column. A null value here
     * indicates that no value has been explicitly set for this column, so
     * ANALYZE should use the default setting.
     *
     * int16 is sufficient for the current max value (MAX_STATISTICS_TARGET).
     */
    int16       attstattarget BKI_DEFAULT(_null_) BKI_FORCE_NULL;
 
    /* Column-level access permissions */
    aclitem     attacl[1] BKI_DEFAULT(_null_);
 
    /* Column-level options */
    text        attoptions[1] BKI_DEFAULT(_null_);
 
    /* Column-level FDW options */
    text        attfdwoptions[1] BKI_DEFAULT(_null_);
 
    /*
     * Missing value for added columns. This is a one element array which lets
     * us store a value of the attribute type here.
     */
    anyarray    attmissingval BKI_DEFAULT(_null_);
#endif
} FormData_pg_attribute;
 
/*
 * ATTRIBUTE_FIXED_PART_SIZE is the size of the fixed-layout,
 * guaranteed-not-null part of a pg_attribute row.  This is in fact as much
 * of the row as gets copied into tuple descriptors, so don't expect you
 * can access the variable-length fields except in a real tuple!
 */
#define ATTRIBUTE_FIXED_PART_SIZE \
    (offsetof(FormData_pg_attribute,attcollation) + sizeof(Oid))
 
/* ----------------
 *      Form_pg_attribute corresponds to a pointer to a tuple with
 *      the format of pg_attribute relation.
 * ----------------
 */
typedef FormData_pg_attribute *Form_pg_attribute;
 
/*
 * FormExtraData_pg_attribute contains (some of) the fields that are not in
 * FormData_pg_attribute because they are excluded by CATALOG_VARLEN.  It is
 * meant to be used by DDL code so that the combination of
 * FormData_pg_attribute (often via tuple descriptor) and
 * FormExtraData_pg_attribute can be used to pass around all the information
 * about an attribute.  Fields can be included here as needed.
 */
typedef struct FormExtraData_pg_attribute
{
    NullableDatum attstattarget;
    NullableDatum attoptions;
} FormExtraData_pg_attribute;
 
DECLARE_UNIQUE_INDEX(pg_attribute_relid_attnam_index, 2658, AttributeRelidNameIndexId, pg_attribute, btree(attrelid oid_ops, attname name_ops));
DECLARE_UNIQUE_INDEX_PKEY(pg_attribute_relid_attnum_index, 2659, AttributeRelidNumIndexId, pg_attribute, btree(attrelid oid_ops, attnum int2_ops));
 
MAKE_SYSCACHE(ATTNAME, pg_attribute_relid_attnam_index, 32);
MAKE_SYSCACHE(ATTNUM, pg_attribute_relid_attnum_index, 128);
 
#ifdef EXPOSE_TO_CLIENT_CODE
 
#define       ATTRIBUTE_IDENTITY_ALWAYS     'a'
#define       ATTRIBUTE_IDENTITY_BY_DEFAULT 'd'
 
#define       ATTRIBUTE_GENERATED_STORED    's'
#define       ATTRIBUTE_GENERATED_VIRTUAL   'v'
 
#endif                          /* EXPOSE_TO_CLIENT_CODE */
 
#endif                          /* PG_ATTRIBUTE_H */