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Re: Add SPLIT PARTITION/MERGE PARTITIONS commands

Dmitry Koval <d.koval@postgrespro.ru>

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From: Dmitry Koval <d.koval@postgrespro.ru>
To: pgsql-hackers@lists.postgresql.org
Date: 2023-12-04T07:52:06Z
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

Hello!

Added commit v21-0004-SPLIT-PARTITION-optimization.patch.

Three already existing commits did not change 
(v21-0001-ALTER-TABLE-MERGE-PARTITIONS-command.patch, 
v21-0002-ALTER-TABLE-SPLIT-PARTITION-command.patch, 
v21-0003-Documentation-for-ALTER-TABLE-SPLIT-PARTITION-ME.patch).

The new commit is an optimization for the SPLIT PARTITION command.

Description of optimization:
1) optimization is used for the SPLIT PARTITION command for tables with 
BY RANGE partitioning in case the partitioning key has a b-tree index;
2) the point of optimization is that, if after dividing of the old 
partition, all its records according to the range conditions must be 
inserted into ONE new partition, then instead of transferring data (from 
the old partition to new partition), the old partition will be renamed.

Example.
Suppose we have a BY RANGE-partitioned table "test" (indexed by 
partitioning key) with a single partition "test_default", which we want 
to split into two partitions ("test_1" and "test_default"), and all 
records should be moved to the "test_1" partition.
When executing the script below, the "test_default" partition will be 
renamed to "test_1".

----
CREATE TABLE test(d date, v text) PARTITION BY RANGE (d);
CREATE TABLE test_default PARTITION OF test DEFAULT;

CREATE INDEX idx_test_d ON test USING btree (d);

INSERT INTO test (d, v)
  SELECT d, 'value_' || md5(random()::text) FROM
   generate_series('2024-01-01', '2024-01-25', interval '10 seconds')
    AS d;

-- Oid of table 'test_default':
SELECT 'test_default'::regclass::oid AS previous_partition_oid;

ALTER TABLE test SPLIT PARTITION test_default INTO
   (PARTITION test_1 FOR VALUES FROM ('2024-01-01') TO ('2024-02-01'),
    PARTITION test_default DEFAULT);

-- Oid of table 'test_1' (should be the same as "previous_partition_oid"):
SELECT 'test_1'::regclass::oid AS current_partition_oid;

DROP TABLE test CASCADE;

-- 
With best regards,
Dmitry Koval

Postgres Professional: http://postgrespro.com