MySQL Bugs: #114512: MySQL 8: Order by with hash join incredibly slow

Bug #114512	MySQL 8: Order by with hash join incredibly slow
Submitted:	29 Mar 2024 9:35	Modified:	17 Jun 2024 9:51
Reporter:	Jakub Szafrański	Email Updates:
Status:	Verified	Impact on me:	None
Category:	MySQL Server: Optimizer	Severity:	S5 (Performance)
Version:	8.3.0, 8.0.36	OS:	Any
Assigned to:		CPU Architecture:	Any

File:	Maximum allowed size is 50MB.
Description:
Privacy:

If the data you need to attach is more than 50MB, you should create a compressed archive of the data, split it to 50MB chunks, and upload each of them as a separate attachment.

To split a large file:

On *nix platforms use the split command e.g. split -b 50MB <my_large_archive> <my_split_archive_prefix>
On windows use WinZip or a similar utility to split the large file

Plans (explain & analyze) for the problematic query

Attachment: 1_plans-regular-query.txt (text/plain), 1.89 KiB.

Plans (explain & analyze) for the query without ORDER BY

Attachment: 2_plans-without-order-by.txt (text/plain), 1.67 KiB.

Plans (explain & analyze) for the query with disabled hash join (via a plan hinter)

Attachment: 3_plans-without-hash-join.txt (text/plain), 1.58 KiB.

Test results - 5.7.44, 8.0.36 and 8.3.0

Attachment: 114512_5.7.44_8.0.36_8.3.0.results (application/octet-stream, text), 39.21 KiB.

Plans (explain & analyze) for the problematic query on 8.4.0

Attachment: hash-join-840.txt (text/plain), 955 bytes.

8.4.0 status variables

Attachment: status_variables.txt (text/plain), 255.49 KiB.

8.4.0 configuration variables

Attachment: variables.txt (text/plain), 405.62 KiB.