Re: Partition-wise join for join between (declaratively) partitioned tables

On Fri, Oct 6, 2017 at 3:07 PM, Ashutosh Bapat
<ashutosh(dot)bapat(at)enterprisedb(dot)com> wrote:
> On Fri, Oct 6, 2017 at 8:45 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> I think this is very good work and I'm excited about the feature. Now
>> I'll wait to see whether the buildfarm, or Tom, yell at me for
>> whatever problems this may still have...
>
> Buildfarm animal prion turned red. Before going into that failure,
> good news is that the other animals are green. So the plans are
> stable.
>
> prion runs the regression with -DRELCACHE_FORCE_RELEASE, which
> destroys a relcache entry as soon as its reference count drops down to
> 0. This destroys everything that's there in corresponding relcache
> entry including partition key information and partition descriptor
> information. find_partition_scheme() and set_relation_partition_info()
> both assume that the relcache information will survive as long as the
> relation lock is held. They do not copy the relevant partitioning
> information but just copy the pointers. That assumption is wrong.
> Because of -DRELCACHE_FORCE_RELEASE, as soon as refcount drops to
> zero, the data in partition scheme and partition bounds goes invalid
> and various checks to see if partition wise join is possible fail.
> That causes partition_join test to fail on prion. But I think, the bug
> could cause crash as well.
>
> The fix is to copy the relevant partitioning information from relcache
> into PartitionSchemeData and RelOptInfo. Here's a quick patch with
> that fix.

Committed. I hope that makes things less red rather than more,
because I'm going to be AFK for a few hours anyway.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
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