Horton

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

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
Cc: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>, Thomas Munro <thomas.munro@enterprisedb.com>, Rafia Sabih <rafia.sabih@enterprisedb.com>, Rajkumar Raghuwanshi <rajkumar.raghuwanshi@enterprisedb.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-09-09T00:58:25Z
Lists: pgsql-hackers 
On Fri, Sep 8, 2017 at 1:38 PM, Ashutosh Bapat
<ashutosh.bapat@enterprisedb.com> wrote:
>> I also confirmed that the partition-pruning patch set works fine with this
>> patch instead of the patch on that thread with the same functionality,
>> which I will now drop from that patch set.  Sorry about the wasted time.
>
> Thanks a lot. Please review the patch in the updated patchset.

In set_append_rel_size(), I don't find the comment too clear (and this
part was taken from Amit's patch, right?).  I suggest:

+    /*
+     * Associate the partitioned tables which are descendents of the table
+     * named in the query with the topmost append path (i.e. the one where
+     * rel->reloptkind is RELOPT_BASEREL).  This ensures that they get properly
+     * locked at execution time.
+     */

I'm a bit suspicious about the fact that there are now executor
changes related to the PlanRowMarks.  If the rowmark's prti is now the
intermediate parent's RT index rather than the top-parent's RT index,
it'd seem like that'd matter somehow.  Maybe it doesn't, because the
code that cares about prti seems to only care about whether it's
different from rti.  But if that's true everywhere, then why even
change this?  I think we might be well off not to tinker with things
that don't need to be changed.

Apart from that concern, now that I understand (from my own failed
attempt and some off-list discussion) why this patch works the way it
does, I think this is in fairly good shape.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Commits

  1. Add test for partitionwise join involving default partition.

  2. Rewrite the code that applies scan/join targets to paths.

  3. Fix code related to partitioning schemes for dropped columns.

  4. Copy information from the relcache instead of pointing to it.

  5. Basic partition-wise join functionality.

  6. Associate partitioning information with each RelOptInfo.

  7. Expand partitioned table RTEs level by level, without flattening.

  8. Set partitioned_rels appropriately when UNION ALL is used.

  9. Remove dedicated B-tree root-split record types.

  10. Assorted preparatory refactoring for partition-wise join.

  11. Teach adjust_appendrel_attrs(_multilevel) to do multiple translations.

  12. Avoid unnecessary single-child Append nodes.

  13. Revisit handling of UNION ALL subqueries with non-Var output columns.