On Thu, Jan 24, 2019 at 08:56:05AM -0300, Alvaro Herrera wrote: > Uh, I didn't think it was necessary nor desirable to rename the flag, > only the user-visible message.
Oh, OK. I have overstated your comment then. Are you fine with the attached instead? The flag name remains the same, and the comment is updated. -- Michael
From 2b9bb74106800b9c9b3fc95fe4f141858abbde02 Mon Sep 17 00:00:00 2001
From: Michael Paquier <mich...@paquier.xyz>
Date: Fri, 25 Jan 2019 19:18:39 +0900
Subject: [PATCH] Simplify 2PC restriction handling for temporary objects
There are two flags used to control access to temporary tables and
access to the temporary namespace of a session, however the first
control flag is actually a concept included in the second. This removes
the flag for temporary table tracking, keeping around only the one at
namespace level.
---
src/backend/access/common/relation.c | 4 ++--
src/backend/access/transam/xact.c | 21 ++++++------------
src/backend/commands/lockcmds.c | 2 +-
src/backend/commands/tablecmds.c | 2 +-
src/include/access/xact.h | 12 +++-------
.../expected/test_extensions.out | 2 +-
src/test/regress/expected/temp.out | 22 +++++++++----------
7 files changed, 26 insertions(+), 39 deletions(-)
diff --git a/src/backend/access/common/relation.c b/src/backend/access/common/relation.c
index beec34f126..41a0051f88 100644
--- a/src/backend/access/common/relation.c
+++ b/src/backend/access/common/relation.c
@@ -71,7 +71,7 @@ relation_open(Oid relationId, LOCKMODE lockmode)
/* Make note that we've accessed a temporary relation */
if (RelationUsesLocalBuffers(r))
- MyXactFlags |= XACT_FLAGS_ACCESSEDTEMPREL;
+ MyXactFlags |= XACT_FLAGS_ACCESSEDTEMPNAMESPACE;
pgstat_initstats(r);
@@ -121,7 +121,7 @@ try_relation_open(Oid relationId, LOCKMODE lockmode)
/* Make note that we've accessed a temporary relation */
if (RelationUsesLocalBuffers(r))
- MyXactFlags |= XACT_FLAGS_ACCESSEDTEMPREL;
+ MyXactFlags |= XACT_FLAGS_ACCESSEDTEMPNAMESPACE;
pgstat_initstats(r);
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 7c3a9c1e89..38434a199e 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -2259,13 +2259,18 @@ PrepareTransaction(void)
/* NOTIFY will be handled below */
/*
- * Don't allow PREPARE TRANSACTION if we've accessed a temporary table in
+ * Don't allow PREPARE TRANSACTION if we've accessed a temporary object in
* this transaction. Having the prepared xact hold locks on another
* backend's temp table seems a bad idea --- for instance it would prevent
* the backend from exiting. There are other problems too, such as how to
* clean up the source backend's local buffers and ON COMMIT state if the
* prepared xact includes a DROP of a temp table.
*
+ * Other objects types, like functions, operators or extensions, share the
+ * same restriction as they should not be created, locked or dropped as
+ * this can mess up with this session or even a follow-up session trying
+ * to use the same temporary namespace.
+ *
* We must check this after executing any ON COMMIT actions, because they
* might still access a temp relation.
*
@@ -2273,22 +2278,10 @@ PrepareTransaction(void)
* cases, such as a temp table created and dropped all within the
* transaction. That seems to require much more bookkeeping though.
*/
- if ((MyXactFlags & XACT_FLAGS_ACCESSEDTEMPREL))
- ereport(ERROR,
- (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
- errmsg("cannot PREPARE a transaction that has operated on temporary tables")));
-
- /*
- * Similarly, PREPARE TRANSACTION is not allowed if the temporary
- * namespace has been involved in this transaction as we cannot allow it
- * to create, lock, or even drop objects within the temporary namespace
- * as this can mess up with this session or even a follow-up session
- * trying to use the same temporary namespace.
- */
if ((MyXactFlags & XACT_FLAGS_ACCESSEDTEMPNAMESPACE))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
- errmsg("cannot PREPARE a transaction that has operated on temporary namespace")));
+ errmsg("cannot PREPARE a transaction that has operated on temporary objects")));
/*
* Likewise, don't allow PREPARE after pg_export_snapshot. This could be
diff --git a/src/backend/commands/lockcmds.c b/src/backend/commands/lockcmds.c
index f4da564e01..43bba717f2 100644
--- a/src/backend/commands/lockcmds.c
+++ b/src/backend/commands/lockcmds.c
@@ -108,7 +108,7 @@ RangeVarCallbackForLockTable(const RangeVar *rv, Oid relid, Oid oldrelid,
*/
relpersistence = get_rel_persistence(relid);
if (relpersistence == RELPERSISTENCE_TEMP)
- MyXactFlags |= XACT_FLAGS_ACCESSEDTEMPREL;
+ MyXactFlags |= XACT_FLAGS_ACCESSEDTEMPNAMESPACE;
/* Check permissions. */
aclresult = LockTableAclCheck(relid, lockmode, GetUserId());
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index e010586dd6..6943af4136 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -13633,7 +13633,7 @@ PreCommit_on_commit_actions(void)
* relations, we can skip truncating ON COMMIT DELETE ROWS
* tables, as they must still be empty.
*/
- if ((MyXactFlags & XACT_FLAGS_ACCESSEDTEMPREL))
+ if ((MyXactFlags & XACT_FLAGS_ACCESSEDTEMPNAMESPACE))
oids_to_truncate = lappend_oid(oids_to_truncate, oc->relid);
break;
case ONCOMMIT_DROP:
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index ed21a13896..426e77846f 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -87,10 +87,10 @@ extern int synchronous_commit;
extern int MyXactFlags;
/*
- * XACT_FLAGS_ACCESSEDTEMPREL - set when a temporary relation is accessed. We
- * don't allow PREPARE TRANSACTION in that case.
+ * XACT_FLAGS_ACCESSEDTEMPNAMESPACE - set when a temporary object is accessed.
+ * We don't allow PREPARE TRANSACTION in that case.
*/
-#define XACT_FLAGS_ACCESSEDTEMPREL (1U << 0)
+#define XACT_FLAGS_ACCESSEDTEMPNAMESPACE (1U << 0)
/*
* XACT_FLAGS_ACQUIREDACCESSEXCLUSIVELOCK - records whether the top level xact
@@ -98,12 +98,6 @@ extern int MyXactFlags;
*/
#define XACT_FLAGS_ACQUIREDACCESSEXCLUSIVELOCK (1U << 1)
-/*
- * XACT_FLAGS_ACCESSEDTEMPNAMESPACE - set when a temporary namespace is
- * accessed. We don't allow PREPARE TRANSACTION in that case.
- */
-#define XACT_FLAGS_ACCESSEDTEMPNAMESPACE (1U << 2)
-
/*
* start- and end-of-transaction callbacks for dynamically loaded modules
*/
diff --git a/src/test/modules/test_extensions/expected/test_extensions.out b/src/test/modules/test_extensions/expected/test_extensions.out
index 1eec5a37d3..b5cbdfcad4 100644
--- a/src/test/modules/test_extensions/expected/test_extensions.out
+++ b/src/test/modules/test_extensions/expected/test_extensions.out
@@ -148,7 +148,7 @@ SELECT create_extension_with_temp_schema();
(1 row)
PREPARE TRANSACTION 'twophase_extension';
-ERROR: cannot PREPARE a transaction that has operated on temporary namespace
+ERROR: cannot PREPARE a transaction that has operated on temporary objects
-- Clean up
DROP TABLE test_ext4_tab;
DROP FUNCTION create_extension_with_temp_schema();
diff --git a/src/test/regress/expected/temp.out b/src/test/regress/expected/temp.out
index d6d8f25141..056e5ecf33 100644
--- a/src/test/regress/expected/temp.out
+++ b/src/test/regress/expected/temp.out
@@ -310,32 +310,32 @@ begin;
create function pg_temp.twophase_func() returns void as
$$ select '2pc_func'::text $$ language sql;
prepare transaction 'twophase_func';
-ERROR: cannot PREPARE a transaction that has operated on temporary namespace
+ERROR: cannot PREPARE a transaction that has operated on temporary objects
-- Function drop
create function pg_temp.twophase_func() returns void as
$$ select '2pc_func'::text $$ language sql;
begin;
drop function pg_temp.twophase_func();
prepare transaction 'twophase_func';
-ERROR: cannot PREPARE a transaction that has operated on temporary namespace
+ERROR: cannot PREPARE a transaction that has operated on temporary objects
-- Operator creation
begin;
create operator pg_temp.@@ (leftarg = int4, rightarg = int4, procedure = int4mi);
prepare transaction 'twophase_operator';
-ERROR: cannot PREPARE a transaction that has operated on temporary namespace
+ERROR: cannot PREPARE a transaction that has operated on temporary objects
-- These generate errors about temporary tables.
begin;
create type pg_temp.twophase_type as (a int);
prepare transaction 'twophase_type';
-ERROR: cannot PREPARE a transaction that has operated on temporary tables
+ERROR: cannot PREPARE a transaction that has operated on temporary objects
begin;
create view pg_temp.twophase_view as select 1;
prepare transaction 'twophase_view';
-ERROR: cannot PREPARE a transaction that has operated on temporary tables
+ERROR: cannot PREPARE a transaction that has operated on temporary objects
begin;
create sequence pg_temp.twophase_seq;
prepare transaction 'twophase_sequence';
-ERROR: cannot PREPARE a transaction that has operated on temporary tables
+ERROR: cannot PREPARE a transaction that has operated on temporary objects
-- Temporary tables cannot be used with two-phase commit.
create temp table twophase_tab (a int);
begin;
@@ -345,19 +345,19 @@ select a from twophase_tab;
(0 rows)
prepare transaction 'twophase_tab';
-ERROR: cannot PREPARE a transaction that has operated on temporary tables
+ERROR: cannot PREPARE a transaction that has operated on temporary objects
begin;
insert into twophase_tab values (1);
prepare transaction 'twophase_tab';
-ERROR: cannot PREPARE a transaction that has operated on temporary tables
+ERROR: cannot PREPARE a transaction that has operated on temporary objects
begin;
lock twophase_tab in access exclusive mode;
prepare transaction 'twophase_tab';
-ERROR: cannot PREPARE a transaction that has operated on temporary tables
+ERROR: cannot PREPARE a transaction that has operated on temporary objects
begin;
drop table twophase_tab;
prepare transaction 'twophase_tab';
-ERROR: cannot PREPARE a transaction that has operated on temporary tables
+ERROR: cannot PREPARE a transaction that has operated on temporary objects
-- Corner case: current_schema may create a temporary schema if namespace
-- creation is pending, so check after that. First reset the connection
-- to remove the temporary namespace, and make sure that non-parallel plans
@@ -374,4 +374,4 @@ SELECT current_schema() ~ 'pg_temp' AS is_temp_schema;
(1 row)
PREPARE TRANSACTION 'twophase_search';
-ERROR: cannot PREPARE a transaction that has operated on temporary namespace
+ERROR: cannot PREPARE a transaction that has operated on temporary objects
--
2.20.1
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