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

On Mon, Oct 9, 2017 at 2:05 AM, Ashutosh Bapat
<ashutosh(dot)bapat(at)enterprisedb(dot)com> wrote:
> On Sat, Oct 7, 2017 at 1:04 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> Committed. I hope that makes things less red rather than more,
>> because I'm going to be AFK for a few hours anyway.
>
> Here's the last patch, dealing with the dummy relations, rebased. With
> this fix every join order of a partitioned join can be considered
> partitioned. (This wasn't the case earlier when dummy relation was
> involved.). So, we can allocate the child-join RelOptInfo array in
> build_joinrel_partition_info(), instead of waiting for an appropriate
> pair to arrive in try_partition_wise_join().

Wouldn't a far more general approach be to allow a partition-wise join
between a partitioned table and an unpartitioned table, considering
the result as partitioned? That seems like it would very often yield
much better query plans than what we have right now, and also make the
need for this particular thing go away.

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