Update description on rule based index selection#6815
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Co-authored-by: Grace Cai <qqzczy@126.com>
Co-authored-by: Grace Cai <qqzczy@126.com>
Co-authored-by: Grace Cai <qqzczy@126.com>
| - 索引的列涵盖了多少访问条件。“访问条件”指的是可以转化为某列范围的 `where` 条件,如果某个索引的列集合涵盖的访问条件越多,那么它在这个维度上更优。 | ||
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| 对于这三种维度,如果某个索引 `idx_a` 在**三个维度上都不比 `idx_b` 差**,且**有一个维度比 `idx_b` 好**,那么就会优先选择 `idx_a`。 | ||
| - 选择该索引读表时,是否需要回表(即该索引生成的计划是 IndexReader 还是 IndexLookupReader)。不用回表的索引在这个维度上优于需要回表的索引。如果均需要回表,则比较索引的列涵盖了多少过滤条件。过滤条件指的是可以根据索引判断的 `where` 条件。如果某个索引的列集合涵盖的访问条件越多,则回表数量越少,那么它在这个维度上越优。 |
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“访问条件”的双引号需要去掉吗
winoros
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We add two examples for the warning message output.
rest LGTM
So what changes should be made to this doc PR? |
…angreeneyes/docs-cn into rule-based-index-selection
I have added the two examples in this PR, please take a look. |
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@Rick-lee01 PTAL |
Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com>
Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com>
Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com>
Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com>
Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com>
Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com>
Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com>
Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com>
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/merge |
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/remove-status LGT1 |
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/merge |
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This pull request has been accepted and is ready to merge. DetailsCommit hash: 4613bdb |
What is changed, added or deleted? (Required)
Update description on rule based index selection.
Closed pingcap/tidb#27230
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Do your changes match any of the following descriptions?