proposal: access a table using multiple indexes #10121
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Codecov Report
@@ Coverage Diff @@
## master #10121 +/- ##
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- Coverage 77.1071% 77.0463% -0.0608%
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Files 412 412
Lines 86337 86348 +11
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- Hits 66572 66528 -44
- Misses 14675 14728 +53
- Partials 5090 5092 +2 |
zz-jason
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/rebuild |
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What problem does this PR solve?
Related issue: #9019
In present TiDB, a SQL statement with conditions involving multiple indexed attributes only uses one of the conditions as the index filter to build access condition, while others are regarded as table filters.But in some cases, it will be better with multiple indexes.
What is changed and how it works?
(1) generate possible access paths using multiple indexes.
(2) using cost model to determine whether to use multiple indexes. We call it
IndexMergelike MySQL(3) if choose IndexMergePath, generate a physical plan and execute.