MySQL Bugs: #120016: Documentation "Exchanging Partitions and Subpartitions with Tables" not mentioning limitation about ALGORITHM=INSTANT.

Bug #120016	Documentation "Exchanging Partitions and Subpartitions with Tables" not mentioning limitation about ALGORITHM=INSTANT.
Submitted:	9 Mar 17:41	Modified:	10 Mar 7:58
Reporter:	Jean-François Gagné	Email Updates:
Status:	Verified	Impact on me:	None
Category:	MySQL Server: Documentation	Severity:	S2 (Serious)
Version:	8.0, 8.4, 9.x	OS:	Any
Assigned to:		CPU Architecture:	Any

Description:
Hi,

the documentation page for "Exchanging Partitions and Subpartitions with Tables" [1a] [1b] [1c] does not mention the limitation of ALGORITHM=INSTANT.

[1a]: https://dev.mysql.com/doc/refman/8.0/en/partitioning-management-exchange.html

[1b]: https://dev.mysql.com/doc/refman/8.4/en/partitioning-management-exchange.html

[1c]: https://dev.mysql.com/doc/refman/9.6/en/partitioning-management-exchange.html

In the documentation page for "ALTER TABLE Statement" [2a] [2b] [2c], we can read:

> After adding a column to a partitioned table using ALGORITHM=INSTANT, it is no longer possible to perform ALTER TABLE ... EXCHANGE PARTITION on the table.

[2a]: https://dev.mysql.com/doc/refman/8.0/en/alter-table.html

[2b]: https://dev.mysql.com/doc/refman/8.4/en/alter-table.html

[2c]: https://dev.mysql.com/doc/refman/9.6/en/alter-table.html

Also in the documentation page for "ALTER TABLE Partition Operations" [3a] [3b] [3c], we can read:

> Once one or more columns have been added to a partitioned table using ALGORITHM=INSTANT, it is no longer possible to exchange partitions with that table.

[3a]: https://dev.mysql.com/doc/refman/8.0/en/alter-table-partition-operations.html

[3b]: https://dev.mysql.com/doc/refman/8.4/en/alter-table-partition-operations.html

[3c]: https://dev.mysql.com/doc/refman/9.6/en/alter-table-partition-operations.html

I would expect the documentation page for "Exchanging Partitions and Subpartitions with Tables", which is the goto place for the procedure about EXCHANGE PARTITION to also mention the limitation of ALGORITHM=INSTANT which is mentioned in the "ALTER TABLE Statement" and "ALTER TABLE Partition Operations" pages.

Note: it looks like the fix for Bug#104970 in Sep 2021 was done at two places ("ALTER TABLE Statement" and "ALTER TABLE Partition Operations"), but not at "Exchanging Partitions and Subpartitions with Tables".

Also, I guess this also applies to dropping a column to a partitioned table using ALGORITHM=INSTANT (I have not tested, but should be clarified in the docs; my guess is that these docs were not reviewed after introducing INSTANT DROP COLUMN in 8.0.29 / in 2022-04-26).

This bug is only a documentation bug, not a feature request to lift this limitation.  Related to this limitation, Bug#95484 shows it is possible to have partitions with different ROW_FORMAT, so lifting this limitation should not be too complicated.

Thanks for looking into this,

Jean-François Gagné

How to repeat:
Check the doc.

Suggested fix:
Update doc "Exchanging Partitions and Subpartitions with Tables".