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: 2025-06-06T07:13:22Z
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.

in createTableConstraints
+ /* Add a pre-cooked default expression. */
+ StoreAttrDefault(newRel, num, def, true);
+
+ /* Store CHECK constraints. */
+ StoreConstraints(newRel, cookedConstraints, false);
Here, StoreConstraints last argument should be set to true?
see also StoreAttrDefault.


+static void
+createTableConstraints(Relation modelRel, Relation newRel)
+ /*
+ * Construct a map from the LIKE relation's attnos to the child rel's.
+ * This re-checks type match etc, although it shouldn't be possible to
+ * have a failure since both tables are locked.
+ */
+ attmap = build_attrmap_by_name(RelationGetDescr(newRel),
+   tupleDesc,
+   false);
+
+ /* Cycle for default values. */
+ for (parent_attno = 1; parent_attno <= tupleDesc->natts; parent_attno++)
+ {
+ Form_pg_attribute attribute = TupleDescAttr(tupleDesc,
+ parent_attno - 1);
+
+ /* Ignore dropped columns in the parent. */
+ if (attribute->attisdropped)
+ continue;
+
+ /* Copy default, if present and it should be copied. */
+ if (attribute->atthasdef)
+ {
+ Node   *this_default = NULL;
+ AttrDefault *attrdef = constr->defval;
+ bool found_whole_row;
+ int16 num;
+ Node   *def;
+
+ /* Find default in constraint structure */
+ for (int i = 0; i < constr->num_defval; i++)
+ {
+ if (attrdef[i].adnum == parent_attno)
+ {
+ this_default = stringToNode(attrdef[i].adbin);
+ break;
+ }
+ }
+ if (this_default == NULL)
+ elog(ERROR, "default expression not found for attribute %d of
relation \"%s\"",
+ parent_attno, RelationGetRelationName(modelRel));
you can use TupleDescGetDefault, build_generation_expression
to simplify the above code.

The attached patch fixes the above issues.
it is based on v41-0001-Implement-ALTER-TABLE-.-MERGE-PARTITIONS-.-comma.patch
----------------------
Do getAttributesList need to care about pg_attribute.attidentity?
currently MERGE PARTITION seems to work fine with identity columns,
this issue i didn't dig deeper.

I am wondering right after createPartitionTable,
do we need a CommandCounterIncrement?
because later moveMergedTablesRows will use the output of createPartitionTable.