lsyscache.c

/*-------------------------------------------------------------------------
 *
 * lsyscache.c
 *	  Convenience routines for common queries in the system catalog cache.
 *
 * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/lsyscache.c,v 1.76 2002/07/12 18:43:18 tgl Exp $
 *
 * NOTES
 *	  Eventually, the index information should go through here, too.
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/tupmacs.h"
#include "catalog/pg_amop.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_shadow.h"
#include "catalog/pg_statistic.h"
#include "catalog/pg_type.h"
#include "nodes/makefuncs.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"


/*				---------- AMOP CACHES ----------						 */

/*
 * op_in_opclass
 *
 *		Return t iff operator 'opno' is in operator class 'opclass'.
 */
bool
op_in_opclass(Oid opno, Oid opclass)
{
	return SearchSysCacheExists(AMOPOPID,
								ObjectIdGetDatum(opclass),
								ObjectIdGetDatum(opno),
								0, 0);
}

/*
 * op_requires_recheck
 *
 *		Return t if operator 'opno' requires a recheck when used as a
 *		member of opclass 'opclass' (ie, this opclass is lossy for this
 *		operator).
 *
 * Caller should already have verified that opno is a member of opclass,
 * therefore we raise an error if the tuple is not found.
 */
bool
op_requires_recheck(Oid opno, Oid opclass)
{
	HeapTuple	tp;
	Form_pg_amop amop_tup;
	bool		result;

	tp = SearchSysCache(AMOPOPID,
						ObjectIdGetDatum(opclass),
						ObjectIdGetDatum(opno),
						0, 0);
	if (!HeapTupleIsValid(tp))
		elog(ERROR, "op_requires_recheck: op %u is not a member of opclass %u",
			 opno, opclass);
	amop_tup = (Form_pg_amop) GETSTRUCT(tp);

	result = amop_tup->amopreqcheck;
	ReleaseSysCache(tp);
	return result;
}

/*				---------- ATTRIBUTE CACHES ----------					 */

/*
 * get_attname
 *
 *		Given the relation id and the attribute number,
 *		return the "attname" field from the attribute relation.
 *
 * Note: returns a palloc'd copy of the string, or NULL if no such operator.
 */
char *
get_attname(Oid relid, AttrNumber attnum)
{
	HeapTuple	tp;

	tp = SearchSysCache(ATTNUM,
						ObjectIdGetDatum(relid),
						Int16GetDatum(attnum),
						0, 0);
	if (HeapTupleIsValid(tp))
	{
		Form_pg_attribute att_tup = (Form_pg_attribute) GETSTRUCT(tp);
		char	   *result;

		result = pstrdup(NameStr(att_tup->attname));
		ReleaseSysCache(tp);
		return result;
	}
	else
		return NULL;
}

/*
 * get_attnum
 *
 *		Given the relation id and the attribute name,
 *		return the "attnum" field from the attribute relation.
 */
AttrNumber
get_attnum(Oid relid, char *attname)
{
	HeapTuple	tp;

	tp = SearchSysCache(ATTNAME,
						ObjectIdGetDatum(relid),
						PointerGetDatum(attname),
						0, 0);
	if (HeapTupleIsValid(tp))
	{
		Form_pg_attribute att_tup = (Form_pg_attribute) GETSTRUCT(tp);
		AttrNumber	result;

		result = att_tup->attnum;
		ReleaseSysCache(tp);
		return result;
	}
	else
		return InvalidAttrNumber;
}

/*
 * get_atttype
 *
 *		Given the relation OID and the attribute number with the relation,
 *		return the attribute type OID.
 */
Oid
get_atttype(Oid relid, AttrNumber attnum)
{
	HeapTuple	tp;

	tp = SearchSysCache(ATTNUM,
						ObjectIdGetDatum(relid),
						Int16GetDatum(attnum),
						0, 0);
	if (HeapTupleIsValid(tp))
	{
		Form_pg_attribute att_tup = (Form_pg_attribute) GETSTRUCT(tp);
		Oid			result;

		result = att_tup->atttypid;
		ReleaseSysCache(tp);
		return result;
	}
	else
		return InvalidOid;
}

/* This routine uses the attname instead of the attnum because it
 * replaces the routine find_atttype, which is called sometimes when
 * only the attname, not the attno, is available.
 */
bool
get_attisset(Oid relid, char *attname)
{
	HeapTuple	tp;

	tp = SearchSysCache(ATTNAME,
						ObjectIdGetDatum(relid),
						PointerGetDatum(attname),
						0, 0);
	if (HeapTupleIsValid(tp))
	{
		Form_pg_attribute att_tup = (Form_pg_attribute) GETSTRUCT(tp);
		bool		result;

		result = att_tup->attisset;
		ReleaseSysCache(tp);
		return result;
	}
	else
		return false;
}

/*
 * get_atttypmod
 *
 *		Given the relation id and the attribute number,
 *		return the "atttypmod" field from the attribute relation.
 */