From 657c098e41b0bb29d30d13d9aa1ac858a07f3493 Mon Sep 17 00:00:00 2001
From: Neil Conway <neilc@samurai.com>
Date: Tue, 7 Jun 2005 07:08:35 +0000
Subject: [PATCH] =?UTF-8?q?Add=20a=20function=20lastval(),=20which=20retur?=
=?UTF-8?q?ns=20the=20value=20returned=20by=20the=20last=20nextval()=20or?=
=?UTF-8?q?=20setval()=20performed=20by=20the=20current=20session.=20Updat?=
=?UTF-8?q?e=20the=20docs,=20add=20regression=20tests,=20and=20bump=20the?=
=?UTF-8?q?=20catalog=20version.=20Patch=20from=20Dennis=20Bj=C3=B6rklund,?=
=?UTF-8?q?=20various=20improvements=20by=20Neil=20Conway.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
---
doc/src/sgml/func.sgml | 27 +++++-
src/backend/commands/sequence.c | 114 ++++++++++++++++++-------
src/include/catalog/catversion.h | 4 +-
src/include/catalog/pg_proc.h | 4 +-
src/include/commands/sequence.h | 3 +-
src/test/regress/expected/sequence.out | 59 +++++++++++++
src/test/regress/sql/sequence.sql | 27 ++++++
7 files changed, 202 insertions(+), 36 deletions(-)
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 5bd29793e81..7eb2c4c6b13 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -1,5 +1,5 @@
<!--
-$PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.251 2005/06/06 16:29:01 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.252 2005/06/07 07:08:34 neilc Exp $
PostgreSQL documentation
-->
@@ -6487,6 +6487,9 @@ SELECT TIMESTAMP 'now'; -- incorrect for use with DEFAULT
<indexterm>
<primary>currval</primary>
</indexterm>
+ <indexterm>
+ <primary>lastval</primary>
+ </indexterm>
<indexterm>
<primary>setval</primary>
</indexterm>
@@ -6519,6 +6522,12 @@ SELECT TIMESTAMP 'now'; -- incorrect for use with DEFAULT
<row>
<entry><literal><function>currval</function>(<type>text</type>)</literal></entry>
<entry><type>bigint</type></entry>
+ <entry>Return value most recently obtained with
+ <function>nextval</function> for specified sequence</entry>
+ </row>
+ <row>
+ <entry><literal><function>lastval</function>()</literal></entry>
+ <entry><type>bigint</type></entry>
<entry>Return value most recently obtained with <function>nextval</function></entry>
</row>
<row>
@@ -6587,6 +6596,22 @@ nextval('foo') <lineannotation>searches search path for <literal>fo
</listitem>
</varlistentry>
+ <varlistentry>
+ <term><function>lastval</function></term>
+ <listitem>
+ <para>
+ Return the value most recently returned by
+ <function>nextval</> in the current session. This function is
+ identical to <function>currval</function>, except that instead
+ of taking the sequence name as an argument it fetches the
+ value of the last sequence that <function>nextval</function>
+ was used on in the current session. It is an error to call
+ <function>lastval</function> if <function>nextval</function>
+ has not yet been called in the current session.
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry>
<term><function>setval</function></term>
<listitem>
diff --git a/src/backend/commands/sequence.c b/src/backend/commands/sequence.c
index 78b9225b83c..5af9ba55b6e 100644
--- a/src/backend/commands/sequence.c
+++ b/src/backend/commands/sequence.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/commands/sequence.c,v 1.122 2005/06/06 20:22:57 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/commands/sequence.c,v 1.123 2005/06/07 07:08:34 neilc Exp $
*
*-------------------------------------------------------------------------
*/
@@ -24,6 +24,7 @@
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/resowner.h"
+#include "utils/syscache.h"
/*
@@ -68,7 +69,13 @@ typedef SeqTableData *SeqTable;
static SeqTable seqtab = NULL; /* Head of list of SeqTable items */
+/*
+ * last_used_seq is updated by nextval() to point to the last used
+ * sequence.
+ */
+static SeqTableData *last_used_seq = NULL;
+static void acquire_share_lock(Relation seqrel, SeqTable seq);
static void init_sequence(RangeVar *relation,
SeqTable *p_elm, Relation *p_rel);
static Form_pg_sequence read_info(SeqTable elm, Relation rel, Buffer *buf);
@@ -400,6 +407,7 @@ nextval(PG_FUNCTION_ARGS)
if (elm->last != elm->cached) /* some numbers were cached */
{
+ last_used_seq = elm;
elm->last += elm->increment;
relation_close(seqrel, NoLock);
PG_RETURN_INT64(elm->last);
@@ -521,6 +529,8 @@ nextval(PG_FUNCTION_ARGS)
elm->last = result; /* last returned number */
elm->cached = last; /* last fetched number */
+ last_used_seq = elm;
+
START_CRIT_SECTION();
/* XLOG stuff */
@@ -602,6 +612,42 @@ currval(PG_FUNCTION_ARGS)
PG_RETURN_INT64(result);
}
+Datum
+lastval(PG_FUNCTION_ARGS)
+{
+ Relation seqrel;
+ int64 result;
+
+ if (last_used_seq == NULL)
+ ereport(ERROR,
+ (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("lastval is not yet defined in this session")));
+
+ /* Someone may have dropped the sequence since the last nextval() */
+ if (!SearchSysCacheExists(RELOID,
+ ObjectIdGetDatum(last_used_seq->relid),
+ 0, 0, 0))
+ ereport(ERROR,
+ (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("lastval is not yet defined in this session")));
+
+ seqrel = relation_open(last_used_seq->relid, NoLock);
+ acquire_share_lock(seqrel, last_used_seq);
+
+ /* nextval() must have already been called for this sequence */
+ Assert(last_used_seq->increment != 0);
+
+ if (pg_class_aclcheck(last_used_seq->relid, GetUserId(), ACL_SELECT) != ACLCHECK_OK)
+ ereport(ERROR,
+ (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+ errmsg("permission denied for sequence %s",
+ RelationGetRelationName(seqrel))));
+
+ result = last_used_seq->last;
+ relation_close(seqrel, NoLock);
+ PG_RETURN_INT64(result);
+}
+
/*
* Main internal procedure that handles 2 & 3 arg forms of SETVAL.
*
@@ -740,6 +786,41 @@ setval_and_iscalled(PG_FUNCTION_ARGS)
}
+/*
+ * If we haven't touched the sequence already in this transaction,
+ * we need to acquire AccessShareLock. We arrange for the lock to
+ * be owned by the top transaction, so that we don't need to do it
+ * more than once per xact.
+ */
+static void
+acquire_share_lock(Relation seqrel, SeqTable seq)
+{
+ TransactionId thisxid = GetTopTransactionId();
+
+ if (seq->xid != thisxid)
+ {
+ ResourceOwner currentOwner;
+
+ currentOwner = CurrentResourceOwner;
+ PG_TRY();
+ {
+ CurrentResourceOwner = TopTransactionResourceOwner;
+ LockRelation(seqrel, AccessShareLock);
+ }
+ PG_CATCH();
+ {
+ /* Ensure CurrentResourceOwner is restored on error */
+ CurrentResourceOwner = currentOwner;
+ PG_RE_THROW();
+ }
+ PG_END_TRY();
+ CurrentResourceOwner = currentOwner;
+
+ /* Flag that we have a lock in the current xact. */
+ seq->xid = thisxid;
+ }
+}
+
/*
* Given a relation name, open and lock the sequence. p_elm and p_rel are
* output parameters.
@@ -748,7 +829,6 @@ static void
init_sequence(RangeVar *relation, SeqTable *p_elm, Relation *p_rel)
{
Oid relid = RangeVarGetRelid(relation, false);
- TransactionId thisxid = GetTopTransactionId();
volatile SeqTable elm;
Relation seqrel;
@@ -796,35 +876,7 @@ init_sequence(RangeVar *relation, SeqTable *p_elm, Relation *p_rel)
seqtab = elm;
}
- /*
- * If we haven't touched the sequence already in this transaction,
- * we need to acquire AccessShareLock. We arrange for the lock to
- * be owned by the top transaction, so that we don't need to do it
- * more than once per xact.
- */
- if (elm->xid != thisxid)
- {
- ResourceOwner currentOwner;
-
- currentOwner = CurrentResourceOwner;
- PG_TRY();
- {
- CurrentResourceOwner = TopTransactionResourceOwner;
-
- LockRelation(seqrel, AccessShareLock);
- }
- PG_CATCH();
- {
- /* Ensure CurrentResourceOwner is restored on error */
- CurrentResourceOwner = currentOwner;
- PG_RE_THROW();
- }
- PG_END_TRY();
- CurrentResourceOwner = currentOwner;
-
- /* Flag that we have a lock in the current xact. */
- elm->xid = thisxid;
- }
+ acquire_share_lock(seqrel, elm);
*p_elm = elm;
*p_rel = seqrel;
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index f10bdab7708..a58ec7b5a57 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -37,7 +37,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.272 2005/05/30 20:59:17 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.273 2005/06/07 07:08:34 neilc Exp $
*
*-------------------------------------------------------------------------
*/
@@ -53,6 +53,6 @@
*/
/* yyyymmddN */
-#define CATALOG_VERSION_NO 200505302
+#define CATALOG_VERSION_NO 200506071
#endif
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index ebf15f8c199..9f5c2d8e0e3 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.363 2005/05/20 01:29:55 neilc Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.364 2005/06/07 07:08:34 neilc Exp $
*
* NOTES
* The script catalog/genbki.sh reads this file and generates .bki
@@ -3644,6 +3644,8 @@ DATA(insert OID = 2557 ( bool PGNSP PGUID 12 f f t f i 1 16 "23" _null_ _
DESCR("convert int4 to boolean");
DATA(insert OID = 2558 ( int4 PGNSP PGUID 12 f f t f i 1 23 "16" _null_ _null_ _null_ bool_int4 - _null_ ));
DESCR("convert boolean to int4");
+DATA(insert OID = 2559 ( lastval PGNSP PGUID 12 f f t f v 0 20 "" _null_ _null_ _null_ lastval - _null_ ));
+DESCR("current value from last used sequence");
/*
diff --git a/src/include/commands/sequence.h b/src/include/commands/sequence.h
index 48017538869..38538236c7a 100644
--- a/src/include/commands/sequence.h
+++ b/src/include/commands/sequence.h
@@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/commands/sequence.h,v 1.31 2005/06/06 17:01:25 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/commands/sequence.h,v 1.32 2005/06/07 07:08:35 neilc Exp $
*
*-------------------------------------------------------------------------
*/
@@ -82,6 +82,7 @@ typedef struct xl_seq_rec
extern Datum nextval(PG_FUNCTION_ARGS);
extern Datum currval(PG_FUNCTION_ARGS);
+extern Datum lastval(PG_FUNCTION_ARGS);
extern Datum setval(PG_FUNCTION_ARGS);
extern Datum setval_and_iscalled(PG_FUNCTION_ARGS);
diff --git a/src/test/regress/expected/sequence.out b/src/test/regress/expected/sequence.out
index 040506d4deb..6e919d1f1de 100644
--- a/src/test/regress/expected/sequence.out
+++ b/src/test/regress/expected/sequence.out
@@ -76,3 +76,62 @@ COMMENT ON SEQUENCE asdf IS 'won''t work';
ERROR: relation "asdf" does not exist
COMMENT ON SEQUENCE sequence_test2 IS 'will work';
COMMENT ON SEQUENCE sequence_test2 IS NULL;
+-- Test lastval()
+CREATE SEQUENCE seq;
+SELECT nextval('seq');
+ nextval
+---------
+ 1
+(1 row)
+
+SELECT lastval();
+ lastval
+---------
+ 1
+(1 row)
+
+SELECT setval('seq', 99);
+ setval
+--------
+ 99
+(1 row)
+
+SELECT lastval();
+ lastval
+---------
+ 99
+(1 row)
+
+CREATE SEQUENCE seq2;
+SELECT nextval('seq2');
+ nextval
+---------
+ 1
+(1 row)
+
+SELECT lastval();
+ lastval
+---------
+ 1
+(1 row)
+
+DROP SEQUENCE seq2;
+-- should fail
+SELECT lastval();
+ERROR: lastval is not yet defined in this session
+CREATE USER seq_user;
+BEGIN;
+SET LOCAL SESSION AUTHORIZATION seq_user;
+CREATE SEQUENCE seq3;
+SELECT nextval('seq3');
+ nextval
+---------
+ 1
+(1 row)
+
+REVOKE ALL ON seq3 FROM seq_user;
+SELECT lastval();
+ERROR: permission denied for sequence seq3
+ROLLBACK;
+DROP USER seq_user;
+DROP SEQUENCE seq;
diff --git a/src/test/regress/sql/sequence.sql b/src/test/regress/sql/sequence.sql
index 07f5765faf2..a8b73c02bf8 100644
--- a/src/test/regress/sql/sequence.sql
+++ b/src/test/regress/sql/sequence.sql
@@ -42,3 +42,30 @@ COMMENT ON SEQUENCE asdf IS 'won''t work';
COMMENT ON SEQUENCE sequence_test2 IS 'will work';
COMMENT ON SEQUENCE sequence_test2 IS NULL;
+-- Test lastval()
+CREATE SEQUENCE seq;
+SELECT nextval('seq');
+SELECT lastval();
+SELECT setval('seq', 99);
+SELECT lastval();
+
+CREATE SEQUENCE seq2;
+SELECT nextval('seq2');
+SELECT lastval();
+
+DROP SEQUENCE seq2;
+-- should fail
+SELECT lastval();
+
+CREATE USER seq_user;
+
+BEGIN;
+SET LOCAL SESSION AUTHORIZATION seq_user;
+CREATE SEQUENCE seq3;
+SELECT nextval('seq3');
+REVOKE ALL ON seq3 FROM seq_user;
+SELECT lastval();
+ROLLBACK;
+
+DROP USER seq_user;
+DROP SEQUENCE seq;
\ No newline at end of file
--
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