On Sat, Apr 4, 2020 at 10:57 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> It's not so surprising that we could get a different result that way
> from a CLOBBER_CACHE_ALWAYS animal like hyrax, since CCA-forced
> cache reloads would cause extra stack expenditure at a lot of places.
> And it could vary depending on totally random details, like the number
> of local variables in seemingly unrelated code.
Oh, yeah. That's unfortunate.
> What is odd is that
> (AFAIR) we've never seen this before. Maybe somebody recently added
> an error cursor callback in a place that didn't have it before, and
> is involved in SQL-function processing? None of the commits leading
> up to the earlier failure look promising for that, though.
The relevant range of commits (e8b1774fc2 to a7b9d24e4e) includes an
ereport change (bda6dedbea) and a couple of "simple expression"
changes (8f59f6b9c0, fbc7a71608) but I don't know exactly why they
would have caused this. It seems at least possible, though, that
changing the return type of functions involved in error reporting
would slightly change the amount of stack space used; and the others
are related to SQL-function processing. Other than experimenting on
that machine, I'm not sure how we could really determine the relevant
factors here.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company