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: pgsql-hackers@lists.postgresql.org
Date: 2025-09-22T07:47:49Z
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 Sat, Sep 20, 2025 at 4:06 AM Dmitry Koval <d.koval@postgrespro.ru> wrote:
>
> Hi, Jiah He!
>
> Thanks!
>
>  >list_intersection seems not right, how can we be sure it deals with
>  >collation correctly?
>
> list_intersection function replaced by new partitions_lists_intersection
> function.
>

hi, more about v60.

+ /*
+ * If new partition has the same name as split partition then we should
+ * rename split partition for reusing name.
+ */
+ if (isSameName)
+ {
+ /*
+ * We must bump the command counter to make the split partition tuple
+ * visible for renaming.
+ */
+ CommandCounterIncrement();
+ /* Rename partition. */
+ sprintf(tmpRelName, "split-%u-%X-tmp", RelationGetRelid(rel), MyProcPid);
+ RenameRelationInternal(splitRelOid, tmpRelName, true, false);
+
+ /*
+ * We must bump the command counter to make the split partition tuple
+ * visible after renaming.
+ */
+ CommandCounterIncrement();
+ }
duplicated CommandCounterIncrement call?


+
+/*
+ * get_list_partvalue_string
+ * A C string representation of one list partition value
+ */
+char *
+get_list_partvalue_string(Const *val)
+{
+ deparse_context context;
+ StringInfo buf = makeStringInfo();
+
+ memset(&context, 0, sizeof(deparse_context));
+ context.buf = buf;
+
+ get_const_expr(val, &context, -1);
+
+ return buf->data;
+}

+ ereport(ERROR,
+ errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
+ errmsg("new partitions do not have value %s but split partition does",
+   searchNull ? "NULL" : get_list_partvalue_string(notFoundVal)));

get_list_partvalue_string seems not quite right, because it won't print Const
node collation info.  However, sometimes we do really need to print the
collation, i think.
give that we can do:
CREATE TABLE x(a text collate "C") PARTITION BY LIST (a collate
case_insensitive);

we can simply call deparse_expression. so I removed the
get_list_partvalue_string.


partitions_lists_intersection
will get all the common Const nodes in two PartitionBoundSpec->listdatums.
but that's expensive, and we only need the first common Const location
for error reporting, so I refactored it too.


I propose to change the function name check_partitions_not_overlap_list
to check_list_partitions_overlap,
what do you think?

I also heavily refactor the test again.
(arrange some error check test code together, combine several tests together,
remove/reduce unnecessary tests).
For example, the below code can be merged together to make it more readable.
SELECT attname, attidentity, attgenerated FROM pg_attribute WHERE
attnum > 0 AND attrelid = 'salespeople2_3'::regclass::oid ORDER BY
attnum;
SELECT attname, attidentity, attgenerated FROM pg_attribute WHERE
attnum > 0 AND attrelid = 'salespeople3_4'::regclass::oid ORDER BY
attnum;
SELECT attname, attidentity, attgenerated FROM pg_attribute WHERE
attnum > 0 AND attrelid = 'salespeople4_5'::regclass::oid ORDER BY
attnum;

please check the attached v60 refactor for SPLIT PARTITION.