MySQL Bugs: #119421: Regression in 8.4 vs 8.0 where an index with a second column being a prefix value is not used for a range scan

Bug #119421	Regression in 8.4 vs 8.0 where an index with a second column being a prefix value is not used for a range scan
Submitted:	18 Nov 12:51	Modified:	3 Dec 11:36
Reporter:	Glyn Astill	Email Updates:
Status:	Duplicate	Impact on me:	None
Category:	MySQL Server: Optimizer	Severity:	S5 (Performance)
Version:	8.4	OS:	Linux
Assigned to:		CPU Architecture:	Any
Tags:	8.4 regression, index prefix, range scan

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

Trace showing the 8.0 behaviour (desired)

Attachment: repo_trace_8.0.txt (text/plain), 10.46 KiB.

Trace showing the 8.4 behaviour (undesired)

Attachment: repro_trace_8.4.txt (text/plain), 20.38 KiB.