Horton

Re: Add SPLIT PARTITION/MERGE PARTITIONS commands

Pavel Borisov <pashkin.elfe@gmail.com>

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From: Pavel Borisov <pashkin.elfe@gmail.com>
To: Alexander Korotkov <aekorotkov@gmail.com>
Cc: Justin Pryzby <pryzby@telsasoft.com>, Dmitry Koval <d.koval@postgrespro.ru>, Alexander Lakhin <exclusion@gmail.com>, pgsql-hackers@lists.postgresql.org, Tomas Vondra <tomas.vondra@enterprisedb.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: 2024-05-17T11:02:40Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Adjust errcode in checkPartition()

  2. Fix usage of palloc() in MERGE/SPLIT PARTITION(s) code

  3. Implement ALTER TABLE ... SPLIT PARTITION ... command

  4. Implement ALTER TABLE ... MERGE PARTITIONS ... command

  5. Calculate agglevelsup correctly when Aggref contains a CTE.

  6. Use PqMsg_* macros in applyparallelworker.c.

  7. Restrict psql meta-commands in plain-text dumps.

  8. Ensure we have a snapshot when updating various system catalogs.

  9. Use specific collation where needed in new test

  10. Expand virtual generated columns in the planner

  11. Virtual generated columns

  12. Define PG_LOGICAL_DIR for path pg_logical/ in data folder

  13. Revert support for ALTER TABLE ... MERGE/SPLIT PARTITION(S) commands

  14. Avoid repeated table name lookups in createPartitionTable()

  15. Provide deterministic order for catalog queries in partition_split.sql

  16. Don't copy extended statistics during MERGE/SPLIT partition operations

  17. Fix the name collision detection in MERGE/SPLIT partition operations

  18. Fix regression tests conflict in 3ca43dbbb6

  19. Add permission check for MERGE/SPLIT partition operations

  20. Fix one more portability shortcoming in new test_pg_dump test.

  21. Inherit parent's AM for partition MERGE/SPLIT operations

  22. Add tab completion for partition MERGE/SPLIT operations

  23. Rename tables in tests of partition MERGE/SPLIT operations

  24. Make new partitions with parent's persistence during MERGE/SPLIT

  25. Document the way partition MERGE/SPLIT operations create new partitions

  26. Change the way ATExecMergePartitions() handles the name collision

  27. Grammar fixes for split/merge partitions code

  28. Checks for ALTER TABLE ... SPLIT/MERGE PARTITIONS ... commands

  29. Fix some grammer errors from error messages and codes comments

  30. Support TZ and OF format codes in to_timestamp().

  31. Support identity columns in partitioned tables

  32. Fix indentation in twophase.c

  33. Fix corner-case planner failure for MERGE.

  34. Doc: fix documentation example for bytea hex output format.

  35. Avoid repeated name lookups during table and index DDL.

Hi, Alexander:

On Fri, 17 May 2024 at 14:05, Alexander Korotkov <aekorotkov@gmail.com>
wrote:

> On Tue, May 14, 2024 at 5:49 PM Justin Pryzby <pryzby@telsasoft.com>
> wrote:
> > On Thu, May 09, 2024 at 12:51:32AM +0300, Alexander Korotkov wrote:
> > > > > However, parent's table extended statistics already covers all its
> > > > > children.
> > > >
> > > > => That's the wrong explanation.  It's not that "stats on the parent
> > > > table cover its children".  It's that there are two types of stats:
> > > > stats for the "table hierarchy" and stats for the individual table.
> > > > That's true for single-column stats as well as for extended stats.
> > > > In both cases, that's indicated by the inh flag in the code and in
> the
> > > > catalog.
> > > >
> > > > The right explanation is that extended stats on partitioned tables
> are
> > > > not similar to indexes.  Indexes on parent table are nothing other
> than
> > > > a mechanism to create indexes on the child tables.  That's not true
> for
> > > > stats.
> > > >
> > > > See also my prior messages
> > > > ZiJW1g2nbQs9ekwK@pryzbyj2023
> > > > Zi5Msg74C61DjJKW@pryzbyj2023
> > >
> > > Yes, I understand that parents pg_statistic entry with stainherit ==
> > > true includes statistics for the children.  I tried to express this by
> > > word "covers".  But you're right, this is the wrong explanation.
> > >
> > > Can I, please, ask you to revise the patch?
> >
> > I tried to make this clear but it'd be nice if someone (Tomas/Alvaro?)
> > would check that this says what's wanted.
>
> Thank you!
>
> I've assembled the patches with the pending fixes.
> 0001 – The patch by Dmitry Koval for fixing detection of name
> collision in SPLIT partition operation.  Also, I found that name
> collision detection doesn't work well for MERGE partitions.  I've
> added fix for that to this patch as well.
> 0002 -– Patch for skipping copy of extended statistics.  I would
> appreciate more feedback about wording, but I'd like to get a correct
> behavior into the source tree sooner.  If the docs and/or comments
> need further improvements, we can fix that later.
>
> I'm going to push both if no objections.
>
Thank you for working on this patch set!

Some minor things:
0001:
partition_split.sql
157 +-- Check that detection, that the new partition has the same name as
one of
158 +-- the merged partitions, works correctly for temporary partitions
Test for split with comment for merge. Maybe better something like:
"Split partition of a temporary table when one of the partitions after
split has the same name as the partition being split"

0002:
analgous -> analogous (maybe better using "like" instead of "analogous to")
heirarchy -> hierarchy

alter_table.sgml:
Maybe in documentation it's better not to provide reasoning, just state how
it works:
for consistency with <command>CREATE TABLE PARTITION OF</command> ->
similar to <command>CREATE TABLE PARTITION OF</command>

Regards,
Pavel Borisov