Horton

Re: Crash in record_type_typmod_compare

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Sait Talha Nisanci <Sait.Nisanci@microsoft.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>, Metin Doslu <Metin.Doslu@microsoft.com>
Date: 2021-03-31T17:10:50Z
Lists: pgsql-hackers 
Sait Talha Nisanci <Sait.Nisanci@microsoft.com> writes:
>> We should probably do HASH_ENTER<https://github.com/postgres/postgres/blob/1509c6fc29c07d13c9a590fbd6f37c7576f58ba6/src/backend/utils/cache/typcache.c#L1974> only after we have a valid entry so that we don't end up with a NULL entry in the cache even if an intermediate error happens. I will share a fix in this thread soon.
> I am attaching this patch.

I see the hazard, but this seems like an expensive way to fix it,
as it forces two hash searches for every insertion.  Couldn't we just
teach record_type_typmod_compare to say "not equal" if it sees a
null tupdesc?

			regards, tom lane

Commits

  1. Fix assign_record_type_typmod().

  2. Improve an error message