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system variables: add tidb_analyze_version #5824

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ti-chi-bot merged 1 commit into from
Jun 24, 2021
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system variables: add tidb_analyze_version #5824

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2 changes: 1 addition & 1 deletion statistics.md
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Expand Up @@ -6,7 +6,7 @@ aliases: ['/docs/dev/statistics/','/docs/dev/reference/performance/statistics/']

# Introduction to Statistics

TiDB uses statistics to decide [which index to choose](/choose-index.md). The `tidb_analyze_version` variable controls the statistics collected by TiDB. Currently, two versions of statistics are supported: `tidb_analyze_version = 1` and `tidb_analyze_version = 2`. In versions before v5.1, the default value of this variable is `1`. In v5.1, the default value of this variable is `2`, which serves as an experimental feature. These two versions include different information in TiDB:
TiDB uses statistics to decide [which index to choose](/choose-index.md). The `tidb_analyze_version` variable controls the statistics collected by TiDB. Currently, two versions of statistics are supported: `tidb_analyze_version = 1` and `tidb_analyze_version = 2`. In versions before v5.1.0, the default value of this variable is `1`. In v5.1.0, the default value of this variable is `2`, which serves as an experimental feature. These two versions include different information in TiDB:
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@qiancai qiancai Jun 23, 2021

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TiDB uses statistics to decide [which index to choose](/choose-index.md). The `tidb_analyze_version` variable controls the statistics collected by TiDB. Currently, two versions of statistics are supported: `tidb_analyze_version = 1` and `tidb_analyze_version = 2`. In versions before v5.1.0, the default value of this variable is `1`. In v5.1.0, the default value of this variable is `2`, which serves as an experimental feature. These two versions include different information in TiDB:
TiDB uses statistics to decide [which index to choose](/choose-index.md). The `tidb_analyze_version` variable controls the statistics collected by TiDB. Currently, two versions of statistics are supported: `tidb_analyze_version = 1` and `tidb_analyze_version = 2`. In versions before v5.1.0, the default value of this variable is `1`. Starting from v5.1.0, the default value of this variable is `2`, which works as an experimental feature. These two versions include different information in TiDB:

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@TomShawn TomShawn Jun 24, 2021 •
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As confirmed with @winoros, it is better to use "in v5.1.0", because in later versions (after the feature is GA) the behavior might change.

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@winoros winoros Jun 24, 2021

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Yes, the default value and the upgrading behavior may be changed in the later sprint and minor version. So we might not need the Starting from

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Ok. For 5.2, let's check this variable again and see if any update is needed. I've made a note here: https://docs.google.com/spreadsheets/d/1ZUUyLNdvnNRSQBkwavYdAoVp8Zo7kRhPoZhlIhWwZ4o/edit#gid=526167010


| Information | Version 1 | Version 2|
| --- | --- | ---|
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8 changes: 8 additions & 0 deletions system-variables.md
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Expand Up @@ -218,6 +218,14 @@ MPP is a distributed computing framework provided by the TiFlash engine, which a
- Default value: `OFF`
- This variable is used to set whether the `AUTO_INCREMENT` property of a column is allowed to be removed by executing `ALTER TABLE MODIFY` or `ALTER TABLE CHANGE` statements. It is not allowed by default.

### tidb_analyze_version <span class="version-mark">New in v5.1.0</span>

- Scope: SESSION | GLOBAL
- Value options: `1` and `2`
- Default value: `2`
- Controls how TiDB collects statistics.
- In versions before v5.1.0, the default value of this variable is `1`. In v5.1.0, the default value of this variable is `2`, which serves as an experimental feature. For detailed introduction, see [Introduction to Statistics](/statistics.md).
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- In versions before v5.1.0, the default value of this variable is `1`. In v5.1.0, the default value of this variable is `2`, which serves as an experimental feature. For detailed introduction, see [Introduction to Statistics](/statistics.md).
- In versions before v5.1.0, the default value of this variable is `1`. Starting from v5.1.0, the default value of this variable is `2`, which works as an experimental feature. For detailed introduction, see [Introduction to Statistics](/statistics.md).


### tidb_auto_analyze_end_time

- Scope: GLOBAL
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