pgsql: Fix old visibility bug in HeapTupleSatisfiesDirty - Mailing list pgsql-committers

From Alvaro Herrera
Subject pgsql: Fix old visibility bug in HeapTupleSatisfiesDirty
Date
Msg-id E1V5Mcz-0001bm-Lw@gemulon.postgresql.org
Whole thread Raw
List pgsql-committers
Fix old visibility bug in HeapTupleSatisfiesDirty

If a tuple is locked but not updated by a concurrent transaction,
HeapTupleSatisfiesDirty would return that transaction's Xid in xmax,
causing callers to wait on it, when it is not necessary (in fact, if the
other transaction had used a multixact instead of a plain Xid to mark
the tuple, HeapTupleSatisfiesDirty would have behave differently and
*not* returned the Xmax).

This bug was introduced in commit 3f7fbf85dc5b42, dated December 1998,
so it's almost 15 years old now.  However, it's hard to see this
misbehave, because before we had NOWAIT the only consequence of this is
that transactions would wait for slightly more time than necessary; so
it's not surprising that this hasn't been reported yet.

Craig Ringer and Andres Freund

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/706f9dd914c64a41e06b5fbfd62d6d6dab43eeb8

Modified Files
--------------
src/backend/utils/time/tqual.c |    3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)


pgsql-committers by date:

Previous
From: Alvaro Herrera
Date:
Subject: pgsql: Fix old visibility bug in HeapTupleSatisfiesDirty
Next
From: Tom Lane
Date:
Subject: pgsql: Make sure float4in/float8in accept all standard spellings of "in