table.c

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/*-------------------------------------------------------------------------
 *
 * table.c
 *    Generic routines for table related code.
 *
 * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/access/table/table.c
 *
 *
 * NOTES
 *    This file contains table_ routines that implement access to tables (in
 *    contrast to other relation types like indexes) that are independent of
 *    individual table access methods.
 *
 *-------------------------------------------------------------------------
 */
 
#include "postgres.h"
 
#include "access/relation.h"
#include "access/table.h"
#include "storage/lmgr.h"
 
static inline void validate_relation_kind(Relation r);
 
/* ----------------
 *      table_open - open a table relation by relation OID
 *
 *      This is essentially relation_open plus check that the relation
 *      is not an index nor a composite type.  (The caller should also
 *      check that it's not a view or foreign table before assuming it has
 *      storage.)
 * ----------------
 */
Relation
table_open(Oid relationId, LOCKMODE lockmode)
{
    Relation    r;
 
    r = relation_open(relationId, lockmode);
 
    validate_relation_kind(r);
 
    return r;
}
 
 
/* ----------------
 *      try_table_open - open a table relation by relation OID
 *
 *      Same as table_open, except return NULL instead of failing
 *      if the relation does not exist.
 * ----------------
 */
Relation
try_table_open(Oid relationId, LOCKMODE lockmode)
{
    Relation    r;
 
    r = try_relation_open(relationId, lockmode);
 
    /* leave if table does not exist */
    if (!r)
        return NULL;
 
    validate_relation_kind(r);
 
    return r;
}
 
/* ----------------
 *      table_openrv - open a table relation specified
 *      by a RangeVar node
 *
 *      As above, but relation is specified by a RangeVar.
 * ----------------
 */
Relation
table_openrv(const RangeVar *relation, LOCKMODE lockmode)
{
    Relation    r;
 
    r = relation_openrv(relation, lockmode);
 
    validate_relation_kind(r);
 
    return r;
}
 
/* ----------------
 *      table_openrv_extended - open a table relation specified
 *      by a RangeVar node
 *
 *      As above, but optionally return NULL instead of failing for
 *      relation-not-found.
 * ----------------
 */
Relation
table_openrv_extended(const RangeVar *relation, LOCKMODE lockmode,
                      bool missing_ok)
{
    Relation    r;
 
    r = relation_openrv_extended(relation, lockmode, missing_ok);
 
    if (r)
        validate_relation_kind(r);
 
    return r;
}
 
/* ----------------
 *      table_close - close a table
 *
 *      If lockmode is not "NoLock", we then release the specified lock.
 *
 *      Note that it is often sensible to hold a lock beyond relation_close;
 *      in that case, the lock is released automatically at xact end.
 *      ----------------
 */
void
table_close(Relation relation, LOCKMODE lockmode)
{
    relation_close(relation, lockmode);
}
 
/* ----------------
 *      validate_relation_kind - check the relation's kind
 *
 *      Make sure relkind is not index or composite type
 * ----------------
 */
static inline void
validate_relation_kind(Relation r)
{
    if (r->rd_rel->relkind == RELKIND_INDEX ||
        r->rd_rel->relkind == RELKIND_PARTITIONED_INDEX ||
        r->rd_rel->relkind == RELKIND_COMPOSITE_TYPE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cannot open relation \"%s\"",
                        RelationGetRelationName(r)),
                 errdetail_relkind_not_supported(r->rd_rel->relkind)));
}