Range Scan Queries Do Not Use Full Width of Composite (Multi-Column) Index
(Doc ID 2585491.1)
Last updated on SEPTEMBER 05, 2019
Applies to:MySQL Server - Version 5.0 and later
Information in this document applies to any platform.
When executing a query with a composite index (that is, an index with multiple columns) and a range condition on a column that is not the last of the index, only part of the index is used to filter the rows. For example:
Visual Explain for the query in the example
This causes the query to perform badly.
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