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

pgsql: Fix old oversight in const-simplification of COALESCE()expressi

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: pgsql-committers(at)postgresql(dot)org
Subject: pgsql: Fix old oversight in const-simplification of COALESCE()expressi
Date: 2010-11-12 20:24:25
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-committers
Fix old oversight in const-simplification of COALESCE() expressions.

Once we have found a non-null constant argument, there is no need to
examine additional arguments of the COALESCE.  The previous coding got it
right only if the constant was in the first argument position; otherwise
it tried to simplify following arguments too, leading to unexpected
behavior like this:

regression=# select coalesce(f1, 42, 1/0) from int4_tbl;
ERROR:  division by zero

It's a minor corner case, but a bug is a bug, so back-patch all the way.



Modified Files
src/backend/optimizer/util/clauses.c |    6 +++++-
1 files changed, 5 insertions(+), 1 deletions(-)

pgsql-committers by date

Next:From: Robert HaasDate: 2010-11-12 21:43:19
Subject: pgsql: Move copydir() prototype into its own header file.
Previous:From: Peter EisentrautDate: 2010-11-12 20:16:41
Subject: pgsql: Improved parallel make support

Privacy Policy | About PostgreSQL
Copyright © 1996-2017 The PostgreSQL Global Development Group