Re: why partition pruning doesn't work?

On 14 June 2018 at 04:10, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> There's still one thing I'm a bit confused about here. I noticed that
> we weren't actually using the partopfamily and partopcintype fields in
> PartitionPruneContext, so I removed them. But that still leaves both
> partsupfunc and partcollation as pointers into the relcache that were
> subject to this hazard. My testing agrees with lousyjack's results
> that both of those were, in fact, being improperly accessed. The OID
> comparison effect I mentioned upthread explains why the buildfarm's
> cache-clobbering members failed to notice any problem with garbage
> partsupfunc data ... but why did we not see any complaints about invalid
> collation OIDs? Tis strange.

FWIW It's not working for me before e23bae82cf3 with
CLOBBER_FREED_MEMORY, CLOBBER_CACHE_ALWAYS and RELCACHE_FORCE_RELEASE,
and:

create table listp (a text) partition by list(a);
create table listp1 partition of listp for values in ('1');
select * from listp where a = (select '1');

I get:

ERROR: cache lookup failed for collation 2139062143

--
David Rowley http://www.2ndQuadrant.com/
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