Function Indexes Not Used Within Correlated Subquery
(Doc ID 2879803.1)
Last updated on JULY 14, 2022
Applies to:MySQL Server - Version 8.0 and later
Information in this document applies to any platform.
MySQL 8.0 supports indexing a function. However, when that function is used within a dependent subquery, the index is not used.
For example, this table has both a function index, and also a generated virtual column with its own explicit index:
Here it has not rewritten the query to use the 'cat' index, but does not pick up the functional_index either.
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