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: 2025-09-15T17:47:15Z
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.

Attachments

On Mon, Sep 15, 2025 at 11:03 AM Alexander Korotkov
<aekorotkov@gmail.com> wrote:
>
> 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?

Additionally, I've made a numerous and small fixes for grammar to the
docs directly to the patchset.

------
Regards,
Alexander Korotkov
Supabase