Horton

Re: Add SPLIT PARTITION/MERGE PARTITIONS commands

jian he <jian.universality@gmail.com>

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From: jian he <jian.universality@gmail.com>
To: Dmitry Koval <d.koval@postgrespro.ru>
Cc: Junwang Zhao <zhjwpku@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2025-06-11T13:22:22Z
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

hi.

+ /* Copy data from merged partitions to new partition. */
+ moveMergedTablesRows(rel, mergingPartitionsList, newPartRel);
+
+ /* Drop the current partitions before attaching the new one. */
+ foreach_ptr(RelationData, mergingPartition, mergingPartitionsList)
+ {
+ ObjectAddress object;
+
+ /* Get relation id before table_close() call. */
+ object.objectId = RelationGetRelid(mergingPartition);
+ object.classId = RelationRelationId;
+ object.objectSubId = 0;
+
+ /* Keep the lock until commit. */
+ table_close(mergingPartition, NoLock);
+
+ performDeletion(&object, DROP_RESTRICT, 0);
+ }
+ list_free(mergingPartitionsList);
In here, should performDeletion last flags have PERFORM_DELETION_INTERNAL?

also this is not ideal, imagine you first did all the main work in
moveMergedTablesRows,
then suddenly error out, saying:

ERROR:  cannot drop table public.pk_1 because other objects depend on it
DETAIL:  view public.v1 depends on table public.pk_1
HINT:  Use DROP ... CASCADE to drop the dependent objects too.
(this errhint, seems not ideal in this context)

We can perform a preliminary check to determine whether dropping a partition is
allowed, and raise an error if it's not. To do it, I invented a new
function, performDeletionCheck to verify whether an object can be
safely dropped.

please check attached, it was based on v43.