*: improve NULL count estimation for single column index #9474
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eurekaka
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## master #9474 +/- ##
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- Coverage 77.5011% 77.2189% -0.2823%
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Files 404 405 +1
Lines 81591 81717 +126
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- Hits 63234 63101 -133
- Misses 13664 13936 +272
+ Partials 4693 4680 -13 |
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@eurekaka please cherry pick this PR to release-2.1 |
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What problem does this PR solve?
An attempt to fix issue #8563.
When column or index contains a lot of null values, our row count estimation for conditions is quite inaccurate. This PR tries to improve the estimation for column stats or single-column index stats. Note that, in #8563, the query is on a multi-column index, and I haven't figured out a way to work in multi-column index scenarios under the current multi-column index framework.
What is changed and how it works?
Histogram,ColumnandIndex;fix periodical panic ofsplit to executor: only show valid columns inshow stats_histograms, I will split this to a separate PR later;stats_histogram#9487Check List
Tests
Code changes
Side effects
Related changes
N/A