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Modify parallel hashagg spill doc #17901

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Jun 27, 2024
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Modify parallel hashagg spill doc #17901

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Merge branch 'master' into hashagg-8.2
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2 changes: 1 addition & 1 deletion configure-memory-usage.md
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Expand Up @@ -149,7 +149,7 @@ TiDB supports disk spill for execution operators. When the memory usage of a SQL

- The disk spill behavior is jointly controlled by the following parameters: [`tidb_mem_quota_query`](/system-variables.md#tidb_mem_quota_query), [`tidb_enable_tmp_storage_on_oom`](/system-variables.md#tidb_enable_tmp_storage_on_oom), [`tmp-storage-path`](/tidb-configuration-file.md#tmp-storage-path), and [`tmp-storage-quota`](/tidb-configuration-file.md#tmp-storage-quota).
- When the disk spill is triggered, TiDB outputs a log containing the keywords `memory exceeds quota, spill to disk now` or `memory exceeds quota, set aggregate mode to spill-mode`.
- Disk spill for the Sort, MergeJoin, and HashJoin operators is introduced in v4.0.0; disk spill for the non-parallel algorithm of the HashAgg operator is introduced in v5.2.0; disk spill for the parallel algorithm of the HashAgg operator is introduced in v8.0.0.
- Disk spill for the Sort, MergeJoin, and HashJoin operators is introduced in v4.0.0; disk spill for the non-parallel algorithm of the HashAgg operator is introduced in v5.2.0; disk spill for the parallel algorithm of the HashAgg operator is introduced in v8.0.0 as an experimental feature and becomes generally available (GA) in v8.2.0. You can control whether to enable the parallel HashAgg algorithm that supports disk spill using the system variable [`tidb_enable_parallel_hashagg_spill`](/system-variables.md#tidb_enable_parallel_hashagg_spill-new-in-v800). This variable will be deprecated in a future release.
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- When the SQL executions containing Sort, MergeJoin, HashJoin, or HashAgg cause OOM, TiDB triggers disk spill by default.

> **Note:**
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6 changes: 1 addition & 5 deletions system-variables.md
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Expand Up @@ -2396,16 +2396,12 @@ mysql> SELECT job_info FROM mysql.analyze_jobs ORDER BY end_time DESC LIMIT 1;

### tidb_enable_parallel_hashagg_spill <span class="version-mark">New in v8.0.0</span>

> **Warning:**
>
> Currently, the feature controlled by this variable is experimental. It is not recommended that you use it in production environments. If you find a bug, you can report an [issue](https://github.com/pingcap/tidb/issues) on GitHub.

- Scope: SESSION | GLOBAL
- Persists to cluster: Yes
- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No
- Type: Boolean
- Default value: `ON`
- This variable controls whether TiDB supports disk spill for the parallel HashAgg algorithm. When it is `ON`, disk spill can be triggered for the parallel HashAgg algorithm. This variable will be deprecated after this feature is generally available in a future release.
- This variable controls whether TiDB supports disk spill for the parallel HashAgg algorithm. When it is `ON`, disk spill can be triggered for the parallel HashAgg algorithm. Starting from v8.2.0, setting it to `OFF` will report an error. This variable will be deprecated in a future release.

### tidb_enable_pipelined_window_function

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