Re: Strange coding in mvdistinct.c
Tom Lane <tgl@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: pgsql-hackers@lists.postgresql.org
Date: 2019-04-15T22:12:24Z
Lists: pgsql-hackers
Oh, and as I continue to grep, I found this in dependencies.c:
dependencies = (MVDependencies *) repalloc(dependencies,
offsetof(MVDependencies, deps)
+ dependencies->ndeps * sizeof(MVDependency));
I'm pretty sure this is an actual bug: the calculation should be
offsetof(MVDependencies, deps)
+ dependencies->ndeps * sizeof(MVDependency *));
because deps is an array of MVDependency* not MVDependency.
This would lead to an overallocation not underallocation, and it's
probably pretty harmless because ndeps can't get too large (I hope;
if it could, this would have O(N^2) performance problems). Still,
you oughta fix it.
(There's a similar calculation later in the file that gets it right.)
regards, tom lane
Commits
-
Fix mvdistinct and dependencies size calculations
- d08c44f7a4ec 12.0 landed