Package: postgresql-debversion
X-Debbugs-CC: la...@debian.org, mat...@debian.org, and...@tao11.riddles.org.uk
Hi,
The current implementation of 'debversion' could be improved for
better performance on hash joins.
There's a missing HASHES property on the = operator declaration that's
stopping it being considered for hash joins. It's not just a matter of
changing one file, it needs a rename, an update script with some sql,
and a change to the default version.
It was discovered because the version is in Join Filter and not Hash
Cond. Also in a test case, the cost estimate for the hash join was sky
high, which suggests that the actual hashing did not do the work it
should be doing.
The queries that gave rise to this filing are located here:
https://salsa.debian.org/lintian/lintian/merge_requests/252
Credit for finding this bug belongs to RhodiumToad from #postgresql,
who was copied on this message. Thank you!
Kind regards,
Felix Lechner
