Skip site navigation (1) Skip section navigation (2)

pgsql: Fix issues with checks for unsupported transaction states inHot

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: pgsql-committers(at)postgresql(dot)org
Subject: pgsql: Fix issues with checks for unsupported transaction states inHot
Date: 2012-08-24 17:09:35
Message-ID: E1T4xO3-0001oi-Bg@gemulon.postgresql.org (view raw or flat)
Thread:
Lists: pgsql-committers
Fix issues with checks for unsupported transaction states in Hot Standby.

The GUC check hooks for transaction_read_only and transaction_isolation
tried to check RecoveryInProgress(), so as to disallow setting read/write
mode or serializable isolation level (respectively) in hot standby
sessions.  However, GUC check hooks can be called in many situations where
we're not connected to shared memory at all, resulting in a crash in
RecoveryInProgress().  Among other cases, this results in EXEC_BACKEND
builds crashing during child process start if default_transaction_isolation
is serializable, as reported by Heikki Linnakangas.  Protect those calls
by silently allowing any setting when not inside a transaction; which is
okay anyway since these GUCs are always reset at start of transaction.

Also, add a check to GetSerializableTransactionSnapshot() to complain
if we are in hot standby.  We need that check despite the one in
check_XactIsoLevel() because default_transaction_isolation could be
serializable.  We don't want to complain any sooner than this in such
cases, since that would prevent running transactions at all in such a
state; but a transaction can be run, if SET TRANSACTION ISOLATION is done
before setting a snapshot.  Per report some months ago from Robert Haas.

Back-patch to 9.1, since these problems were introduced by the SSI patch.

Kevin Grittner and Tom Lane, with ideas from Heikki Linnakangas

Branch
------
REL9_2_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/c3ca786df656d447ca02d51ed3a888468ed6e88d

Modified Files
--------------
src/backend/commands/variable.c      |   13 +++++++++++--
src/backend/storage/lmgr/predicate.c |   13 +++++++++++++
src/backend/utils/init/postinit.c    |    9 +++++++++
3 files changed, 33 insertions(+), 2 deletions(-)

pgsql-committers by date

Next:From: Peter EisentrautDate: 2012-08-25 02:52:51
Subject: pgsql: Some spelling adjustments in release notes
Previous:From: Peter EisentrautDate: 2012-08-24 04:19:28
Subject: pgsql: Put options on man page and in help output in slightly betteror

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group