Bug #99593 | Performance issues in 8.0.20 | ||
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Submitted: | 15 May 2020 16:05 | Modified: | 25 May 2020 11:17 |
Reporter: | Billy Sullivan | Email Updates: | |
Status: | Closed | Impact on me: | |
Category: | MySQL Server: InnoDB storage engine | Severity: | S5 (Performance) |
Version: | 8.0.20 | OS: | Ubuntu (20.04) |
Assigned to: | CPU Architecture: | Any |
[15 May 2020 16:05]
Billy Sullivan
[16 May 2020 9:10]
MySQL Verification Team
Thanks for the test data. Found a workaround on 8.0.20 to improve the speed: SET GLOBAL internal_tmp_mem_storage_engine=MEMORY; It seems this bug is a duplicate of internally filed: Bug 30562964 : 8.0.18: PERFORMANCE REGRESSION IN SELECT DISTINCT which was introduced in 8.0.18 and fixed in 8.0.21. I've confirmed that on 8.0.17 and current internal build of 8.0. the performance regression is gone. So changing the internal_tmp_mem_storage_engine should help until 8.0.21 is released (no ETA).
[16 May 2020 12:16]
Billy Sullivan
Thanks Shane, that worked!
[25 May 2020 11:17]
Erlend Dahl
Already fixed in the upcoming 8.0.21 release under the heading of Bug#30562964 8.0.18: PERFORMANCE REGRESSION IN SELECT DISTINCT
[1 Oct 2021 13:05]
Derli Dias Campos Junior
By running: SET GLOBAL internal_tmp_mem_storage_engine=MEMORY; The variable value won't be changed to MEMORY, it will stay as TempTable Any suggestion?