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Introduce sequence_*() access functions

Similarly to tables and indexes, these functions are able to open
relations with a sequence relkind, which is useful to make a distinction
with the other relation kinds.  Previously, commands/sequence.c used a
mix of table_{close,open}() and relation_{close,open}() routines when
manipulating sequence relations, so this clarifies the code.

A direct effect of this change is to align the error messages produced
when attempting DDLs for sequences on relations with an unexpected
relkind, like a table or an index with ALTER SEQUENCE, providing an
extra error detail about the relkind of the relation used in the DDL
query.

Author: Michael Paquier
Reviewed-by: Tomas Vondra
Discussion: https://postgr.es/m/ZWlohtKAs0uVVpZ3@paquier.xyz
This commit is contained in:
Michael Paquier
2024-02-26 16:04:59 +09:00
parent 025f0a6f91
commit 449e798c77
8 changed files with 140 additions and 20 deletions

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#-------------------------------------------------------------------------
#
# Makefile
# Makefile for access/sequence
#
# IDENTIFICATION
# src/backend/access/sequence/Makefile
#
#-------------------------------------------------------------------------
subdir = src/backend/access/sequence
top_builddir = ../../../..
include $(top_builddir)/src/Makefile.global
OBJS = sequence.o
include $(top_srcdir)/src/backend/common.mk

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# Copyright (c) 2022-2024, PostgreSQL Global Development Group
backend_sources += files(
'sequence.c',
)

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/*-------------------------------------------------------------------------
*
* sequence.c
* Generic routines for sequence-related code.
*
* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/access/sequence/sequence.c
*
*
* NOTES
* This file contains sequence_ routines that implement access to sequences
* (in contrast to other relation types like indexes).
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/relation.h"
#include "access/sequence.h"
#include "storage/lmgr.h"
static inline void validate_relation_kind(Relation r);
/* ----------------
* sequence_open - open a sequence relation by relation OID
*
* This is essentially relation_open plus check that the relation
* is a sequence.
* ----------------
*/
Relation
sequence_open(Oid relationId, LOCKMODE lockmode)
{
Relation r;
r = relation_open(relationId, lockmode);
validate_relation_kind(r);
return r;
}
/* ----------------
* sequence_close - close a sequence
*
* 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
sequence_close(Relation relation, LOCKMODE lockmode)
{
relation_close(relation, lockmode);
}
/* ----------------
* validate_relation_kind - check the relation's kind
*
* Make sure relkind is from an index
* ----------------
*/
static inline void
validate_relation_kind(Relation r)
{
if (r->rd_rel->relkind != RELKIND_SEQUENCE)
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("cannot open relation \"%s\"",
RelationGetRelationName(r)),
errdetail_relkind_not_supported(r->rd_rel->relkind)));
}