Re: hyrax vs. RelationBuildPartitionDesc

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> As a parenthetical note, I observe that relcache.c seems to know
> almost nothing about rd_partcheck. rd_partkey and rd_partdesc both
> have handling in RelationClearRelation(), but rd_partcheck does not,
> and I suspect that's wrong. So the problems are probably not confined
> to the relcache-drop-time problem that you observed.

I concluded that that's not parenthetical but pretty relevant...

Attached is a revised version of Amit's patch at [1] that makes these
data structures be treated more similarly. I also added some Asserts
and comment improvements to address the complaints I made upthread about
under-documentation of all this logic.

I also cleaned up the problem the code had with failing to distinguish
"partcheck list is NIL" from "partcheck list hasn't been computed yet".
For a relation with no such constraints, generate_partition_qual would do
the full pushups every time. I'm not sure if the case actually occurs
commonly enough that that's a performance problem, but failure to account
for it made my added assertions fall over :-( and I thought fixing it
was better than weakening the assertions.

I haven't made back-patch versions yet. I'd expect they could be
substantially the same, except the two new fields have to go at the
end of struct RelationData to avoid ABI breaks.

Oh: we might also need some change in RelationCacheInitializePhase3,
depending on the decision about [2].

regards, tom lane

[1] https://www.postgresql.org/message-id/036852f2-ba7f-7a1f-21c6-00bc3515eda3@lab.ntt.co.jp
[2] https://www.postgresql.org/message-id/5706.1555093031@sss.pgh.pa.us