8.0.18 to 8.0.20 Shows Performance Regression of SELECT DISTINCT
(Doc ID 2613353.1)
Last updated on MAY 11, 2020
Applies to:MySQL Server - Version 8.0 and later
Information in this document applies to any platform.
The symptom can be seen in queries like this, who process a large number of rows with many duplicates:
SELECT DISTINCT a,b,c,d,e,f,g,h,i,j FROM t;
8.0.18 takes around 5x longer than 8.0.17 and earlier versions.
8.0.18, 8.0.19, or 8.0.20 was installed.
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