tidb_query: fix analyze column inconsistent behavior betwen TiDB and TiKV #6055
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Signed-off-by: Lonng <heng@lonng.org>
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What does this PR do? |
lonng
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@eurekaka PTAL |
breezewish
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Nov 27, 2019
iosmanthus
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Nov 27, 2019
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/merge |
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Your auto merge job has been accepted, waiting for 5974 |
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/run-all-tests |
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Should this be cherry-picked to 3.0? |
lonng
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needs-cherry-pick-release-3.0
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/run-cherry-picker |
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cherry pick to release-3.1 in PR #6095 |
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cherry pick to release-3.0 in PR #6096 |
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…TiKV (tikv#6055) Signed-off-by: Lonng <heng@lonng.org>
zhang555
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…TiKV (tikv#6055) Signed-off-by: Lonng <heng@lonng.org>
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Signed-off-by: Lonng heng@lonng.org
What have you changed?
The TiKV has inconsistent behavior with TiDB about analyzing column. see:
https://github.com/pingcap/tidb/blob/eae41adc0cd4a617d792a8bb426033c433a70527/statistics/sample.go#L173
The TiDB assumes samples will keep order with the original data order if the samples count greater than the
max_sample_count. But TiKV replaces the original data if the index conflict, which breaks the assumption.According to the TiDB logic, we should remove the item which index conflected, and append the new item to the samples.
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