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tidb: update the default value of tidb_analyze_column_options (#22198) #22309

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tidb: update the default value of tidb_analyze_column_options (#22198) #22309

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a87fe09
tidb: update the default value of tidb_analyze_column_options
0xPoe Dec 17, 2025
a845313
Update system-variables.md
0xPoe Dec 22, 2025
f647703
fix: add N/A
0xPoe Dec 22, 2025
2b23c9a
Update system-variables.md
qiancai Jan 7, 2026
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5 changes: 3 additions & 2 deletions system-variables.md
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Expand Up @@ -1087,13 +1087,14 @@ MPP is a distributed computing framework provided by the TiFlash engine, which a
>
> - This variable only works when [`tidb_analyze_version`](#tidb_analyze_version-new-in-v510) is set to `2`.
> - If you upgrade your TiDB cluster from a version earlier than v8.3.0 to v8.3.0 or later, this variable is set to `ALL` by default to keep the original behavior.
> - Starting from v8.3.0, for a newly deployed TiDB cluster, this variable is set to `PREDICATE` by default.
> - For a newly deployed TiDB cluster from v8.3.0 to v8.5.4, this variable is set to `PREDICATE` by default.
> - For a newly deployed TiDB cluster from v8.5.5 and v9.0.0 onwards, this variable is set to `ALL` by default.

- Scope: GLOBAL
- Persists to cluster: Yes
- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No
- Type: Enumeration
- Default value: `PREDICATE`
- Default value: `ALL`
- Value options:`ALL`, `PREDICATE`
- This variable controls the behavior of the `ANALYZE TABLE` statement. Setting it to `PREDICATE` means only collecting statistics for [predicate columns](/statistics.md#collect-statistics-on-some-columns); setting it to `ALL` means collecting statistics for all columns. In scenarios where OLAP queries are used, it is recommended to set it to `ALL`, otherwise collecting statistics can result in a significant drop in query performance.
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For better clarity, I suggest rephrasing the last part of this sentence. The current wording 'otherwise collecting statistics can result in a significant drop in query performance' is a bit confusing. It could be interpreted as 'collecting statistics is bad if not set to ALL'. A clearer phrasing would explain why the performance drops.

Suggested change
- This variable controls the behavior of the `ANALYZE TABLE` statement. Setting it to `PREDICATE` means only collecting statistics for [predicate columns](/statistics.md#collect-statistics-on-some-columns); setting it to `ALL` means collecting statistics for all columns. In scenarios where OLAP queries are used, it is recommended to set it to `ALL`, otherwise collecting statistics can result in a significant drop in query performance.
- This variable controls the behavior of the `ANALYZE TABLE` statement. Setting it to `PREDICATE` means only collecting statistics for [predicate columns](/statistics.md#collect-statistics-on-some-columns); setting it to `ALL` means collecting statistics for all columns. In scenarios where OLAP queries are used, it is recommended to set it to `ALL` to avoid a significant drop in query performance that might result from incomplete statistics.
References
  1. The suggested change improves the clarity and readability of the documentation, making it easier for users to understand the impact of the variable setting. This aligns with the style guide's emphasis on clarity and simplicity. (link)


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4 changes: 2 additions & 2 deletions tidb-performance-tuning-config.md
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Expand Up @@ -61,7 +61,7 @@ The following table outlines the impact of specific system variable configuratio
| [`tidb_enable_instance_plan_cache`](/system-variables.md#tidb_enable_instance_plan_cache-new-in-v840) and [`tidb_instance_plan_cache_max_size`](/system-variables.md#tidb_instance_plan_cache_max_size-new-in-v840)| Use instance-level plan cache instead of session-level caching. This significantly improves performance for workloads with high connection counts or frequent prepared statement usage. | This is an experimental feature. Test in non-production environments first and monitor memory usage as the plan cache size increases. |
| [`tidb_enable_non_prepared_plan_cache`](/system-variables.md#tidb_enable_non_prepared_plan_cache)| Enable the [Non-prepared plan cache](/sql-non-prepared-plan-cache.md) feature to reduce compile costs for applications that do not use prepared statements. | N/A |
| [`tidb_ignore_prepared_cache_close_stmt`](/system-variables.md#tidb_ignore_prepared_cache_close_stmt-new-in-v600)| Cache plans for applications that use prepared statements but close the plan after each execution. | N/A |
| [`tidb_analyze_column_options`](/system-variables.md#tidb_analyze_column_options-new-in-v830)| Collect statistics for all columns to avoid suboptimal execution plans due to missing column statistics. By default, TiDB only collects statistics for [predicate columns](/statistics.md#collect-statistics-on-some-columns). | Setting this variable to `'ALL'` can cause more resource usage for the `ANALYZE TABLE` operation compared with the default value `'PREDICATE'`. |
| [`tidb_analyze_column_options`](/system-variables.md#tidb_analyze_column_options-new-in-v830)| Collect statistics for all columns to avoid suboptimal execution plans due to missing column statistics. | N/A |
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The note for tidb_analyze_column_options has been changed to N/A. While the previous note was outdated due to the change in the default value, providing no note at all reduces the completeness of the documentation. A brief note explaining the trade-off of using the non-default PREDICATE value would be helpful for users.

Suggested change
| [`tidb_analyze_column_options`](/system-variables.md#tidb_analyze_column_options-new-in-v830)| Collect statistics for all columns to avoid suboptimal execution plans due to missing column statistics. | N/A |
| [`tidb_analyze_column_options`](/system-variables.md#tidb_analyze_column_options-new-in-v830)| Collect statistics for all columns to avoid suboptimal execution plans due to missing column statistics. | Setting this variable to `PREDICATE` can reduce resource usage for the `ANALYZE TABLE` operation, but might lead to suboptimal execution plans. |
References
  1. The documentation should be complete. Replacing a useful note with 'N/A' reduces completeness. The suggestion provides a concise and helpful note about the trade-offs of the available options. (link)

| [`tidb_stats_load_sync_wait`](/system-variables.md#tidb_stats_load_sync_wait-new-in-v540)| Increase the timeout for synchronously loading statistics from the default 100 milliseconds to 2 seconds. This ensures TiDB loads the necessary statistics before query compilation. | Increasing this value leads to a longer synchronization wait time before query compilation. |
| [`tidb_opt_limit_push_down_threshold`](/system-variables.md#tidb_opt_limit_push_down_threshold)| Increase the threshold that determines whether to push the `Limit` or `TopN` operator down to TiKV. | When multiple index options exist, increasing this variable makes the optimizer favor indexes that can optimize the `ORDER BY` and `Limit` operators. |
| [`tidb_opt_derive_topn`](/system-variables.md#tidb_opt_derive_topn-new-in-v700)| Enable the optimization rule of [Deriving TopN or Limit from window functions](/derive-topn-from-window.md). | This is limited to the `ROW_NUMBER()` window function. |
Expand Down Expand Up @@ -559,4 +559,4 @@ To improve TiKV performance, configure the thread pools based on your instance's
apply-pool-size = 4
store-pool-size = 4
store-io-pool-size = 2
```
```