Horton

Re: Add SPLIT PARTITION/MERGE PARTITIONS commands

Alexander Korotkov <aekorotkov@gmail.com>

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From: Alexander Korotkov <aekorotkov@gmail.com>
To: Dmitry Koval <d.koval@postgrespro.ru>
Cc: jian he <jian.universality@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2025-09-15T08:03:54Z
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 Dmitry.

On Mon, Sep 1, 2025 at 2:04 PM Dmitry Koval <d.koval@postgrespro.ru> wrote:
> Hi!
> Thank you for the notes and patch!

Some additional notes from me.

1) src/backend/parser/parse_utilcmd.c includes are not alphabetically
ordered here
+#include "partitioning/partdesc.h"
+#include "partitioning/partbounds.h"

2) There is unicode dash in the comment of ATExecMergePartitions() here.  I
suggest we should stick to ascii.

+   /*
+    * Check ownership of merged partitions — partitions with different
+    * owners cannot be merged. Also, collect the OIDs of these partitions
+    * during the check.
+    */

3) Regarding 17bcf4f545, I see btnamecmp() is collation-aware.  Should we
also specify COLLATE "C" every time we do "ORDER BY relname"?

4) This comment sounds misleading.  Probably it should say "are contained".

+/*
+ * check_parent_values_in_new_partitions
+ *
+ * (function for BY LIST partitioning)
+ *
+ * Checks that all values of split partition (with Oid partOid) contains
in new
+ * partitions.
+ *

5) Given what latter items say, I think the 1. should say "The DEFAULT
partition must be at most one."

/*
 * check_partitions_for_split
 *
 * Checks new partitions for SPLIT PARTITIONS command:
 * 1. DEFAULT partition should be one.

6) Regarding the isolation tests.  I see we are exercising INSERTs and
intra-partition UPDATEs.  Should we also try some cross-partition UPDATEs?

------
Regards,
Alexander Korotkov
Supabase