add system variable 'tidb_enable_clustered_index' for v5.0#4385
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@zhangjinpeng1987 PTAL |
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Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com>
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| - 这个变量用于控制是否开启 clustered index 特性。 | ||
| - 该特性只适用于新创建的表，对于已经创建的旧表不会有影响。 | ||
| - 该特性只适用于主键为单列非 INT 类型的表和主键为多列的表，对于无主键的表和主键是单列 INT 类型的表不会有影响。 | ||
| - 特性启用以后，row value 会直接存储在主键上，而不再是存储在系统内部分配的 row key 上，然后用额外创建的主键索引指向 row key。 |
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| - 特性启用以后，row value 会直接存储在主键上，而不再是存储在系统内部分配的 row key 上，然后用额外创建的主键索引指向 row key。 | |
| - 特性启用以后，行值会直接存储在主键上，而不再存储在系统内部分配的 row key 上（再用额外创建的主键索引指向该 row key）。 |
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'行值' is used for different meanings in the doc.
| 对性能的影响主要体现在以下几个方面: | ||
| - 插入的时候会减少一个 index key 的写入。 | ||
| - 使用主键做为等值条件查询的时候，会节省一次读取请求。 | ||
| - 使用单列主键做为范围条件条件查询的时候，可以节省多次读取请求。 |
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| - 使用单列主键做为范围条件条件查询的时候，可以节省多次读取请求。 | |
| - 使用单列主键做为范围条件查询的时候，可以节省多次读取请求。 |
TomShawn
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Aug 31, 2020
| - 这个变量用于控制是否开启 Clustered Index 特性。 | ||
| - 该特性只适用于新创建的表，对于已经创建的旧表不会有影响。 | ||
| - 该特性只适用于主键为单列非 INT 类型的表和主键为多列的表。对于无主键的表和主键是单列 INT 类型的表不会有影响。 | ||
| - 特性启用以后，row value 会直接存储在主键上，而不再是存储在系统内部分配的 row key 上，并用额外创建的主键索引指向 row key。 |
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- row value 和 row key 没有对应的中文表达吗？如果非术语，建议使用中文。
- 如果
并用额外创建的主键索引指向 row key是被不再是否定的一部分，这么写读者可能会认为不再是存储在系统内部分配的 row key 上与并用额外创建的主键索引指向 row key是并列关系。
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@TomShawn PTAL |
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Sep 1, 2020
TomShawn
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TomShawn
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Rest LGTM |
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@TomShawn PTAL |
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add system variable 'tidb_enable_clustered_index' for v5.0
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