From cf297024ae7f5ac49d386e25bf52a2f7605dce71 Mon Sep 17 00:00:00 2001 From: nolouch Date: Wed, 3 Jun 2026 13:17:23 -0700 Subject: [PATCH 01/10] docs: add statement summary system variables --- statement-summary-tables.md | 4 ++++ system-variable-reference.md | 16 ++++++++++++++++ system-variables.md | 22 ++++++++++++++++++++++ 3 files changed, 42 insertions(+) diff --git a/statement-summary-tables.md b/statement-summary-tables.md index db190136c129c..ab203ac9f8e12 100644 --- a/statement-summary-tables.md +++ b/statement-summary-tables.md @@ -88,6 +88,7 @@ The following is a sample output of querying `statements_summary`: > > - In TiDB, the time unit of fields in statement summary tables is nanosecond (ns), whereas in MySQL the time unit is picosecond (ps). > - Starting from v7.5.1 and v7.6.0, for clusters with [resource control](/tidb-resource-control-ru-groups.md) enabled, `statements_summary` will be aggregated by resource group, for example, the same statements executed in different resource groups will be collected as different records. +> - Starting from v8.5.7, you can use [`tidb_stmt_summary_group_by_user`](/system-variables.md#tidb_stmt_summary_group_by_user-new-in-v857) to control whether to further aggregate statement summaries by execution user. When the variable value is `ON`, the same SQL digest executed by different users is collected as different records, and the `SAMPLE_USER` field of each record indicates the execution user corresponding to the record. ## `statements_summary_history` @@ -145,6 +146,8 @@ The following system variables are used to control the statement summary: - `tidb_stmt_summary_max_sql_length`: Specifies the longest display length of `DIGEST_TEXT` and `QUERY_SAMPLE_TEXT`. The default value is `4096`. - `tidb_stmt_summary_internal_query`: Determines whether to count the TiDB SQL statements. `1` means to count, and `0` means not to count. The default value is `0`. +- `tidb_stmt_summary_group_by_user`: Determines whether to further aggregate statement summaries by execution user. `1` means to aggregate by user, and `0` means not to aggregate by user. The default value is `0`. After this variable is enabled, the same SQL digest executed by different users is aggregated into different rows, which might increase the number of statement summary records and memory usage. Modifying this variable clears the current in-memory statement summary data. +- `tidb_stmt_summary_persist_evicted`: Determines whether to write statement summary records that are evicted by LRU to the statement summary log after [statements summary persistence](#persist-statements-summary) is enabled. `1` means to write, and `0` means not to write. The default value is `0`. After this variable is enabled, the log contains JSON records marked with `"evicted": true`, and the amount of logs increases as LRU evictions become more frequent. An example of the statement summary configuration is shown as follows: @@ -262,6 +265,7 @@ After statements summary persistence is enabled, the memory keeps only the curre > > - When statements summary persistence is enabled, the `tidb_stmt_summary_history_size` configuration described in the [Parameter configuration](#parameter-configuration) section will no longer take effect because the memory does not keep the history data. Instead, the following three configurations will be used to control the retention period and size of history data for persistence: [`tidb_stmt_summary_file_max_days`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_days-new-in-v660), [`tidb_stmt_summary_file_max_size`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_size-new-in-v660), and [`tidb_stmt_summary_file_max_backups`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_backups-new-in-v660). > - The smaller the value of `tidb_stmt_summary_refresh_interval`, the more immediate data is written to the disk. However, this also means more redundant data is written to the disk. +> - Starting from v8.5.7, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. The written JSON records are marked with `"evicted": true` for downstream log consumers to identify and are not returned as query results of `statements_summary_history` or `cluster_statements_summary_history`. diff --git a/system-variable-reference.md b/system-variable-reference.md index 76a846ad2b039..9dd862baee3c4 100644 --- a/system-variable-reference.md +++ b/system-variable-reference.md @@ -3949,6 +3949,14 @@ Referenced in: - [TiDB Configuration File](/tidb-configuration-file.md) - [TiDB 6.6.0 Release Notes](/releases/release-6.6.0.md) +### tidb_stmt_summary_group_by_user + +Referenced in: + +- [SHOW [GLOBAL|SESSION] VARIABLES](/sql-statements/sql-statement-show-variables.md) +- [Statement Summary Tables](/statement-summary-tables.md) +- [System Variables](/system-variables.md#tidb_stmt_summary_group_by_user-new-in-v857) + ### tidb_stmt_summary_history_size Referenced in: @@ -3992,6 +4000,14 @@ Referenced in: - [TiDB 5.0.4 Release Notes](/releases/release-5.0.4.md) - [TiDB 4.0.14 Release Notes](/releases/release-4.0.14.md) +### tidb_stmt_summary_persist_evicted + +Referenced in: + +- [SHOW [GLOBAL|SESSION] VARIABLES](/sql-statements/sql-statement-show-variables.md) +- [Statement Summary Tables](/statement-summary-tables.md) +- [System Variables](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) + ### tidb_stmt_summary_refresh_interval Referenced in: diff --git a/system-variables.md b/system-variables.md index c16e0dc2ee434..22e9e628866ac 100644 --- a/system-variables.md +++ b/system-variables.md @@ -6330,6 +6330,17 @@ For details, see [Identify Slow Queries](/identify-slow-queries.md). +### tidb_stmt_summary_group_by_user New in v8.5.7 + +- Scope: GLOBAL +- Persists to cluster: Yes +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No +- Type: Boolean +- Default value: `OFF` +- This variable controls whether to include the user that executes SQL statements as an aggregation dimension in [statement summary tables](/statement-summary-tables.md). When the variable value is `OFF`, the same SQL digest executed by different users is aggregated into the same row, and the `SAMPLE_USER` field displays one sampled user. When the variable value is `ON`, the same SQL digest executed by different users is aggregated into different rows, and the `SAMPLE_USER` field of each row indicates the execution user corresponding to the row. +- Modifying this variable clears the current in-memory statement summary data because data before and after the modification uses different aggregation dimensions. Historical data that has been persisted to the disk is not affected. +- After this variable is enabled, the number of statement summary records might increase with the number of different execution users for the same SQL digest, which increases memory usage. + ### tidb_stmt_summary_history_size New in v4.0 > **Note:** @@ -6405,6 +6416,17 @@ For details, see [Identify Slow Queries](/identify-slow-queries.md). +### tidb_stmt_summary_persist_evicted New in v8.5.7 + +- Scope: GLOBAL +- Persists to cluster: Yes +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No +- Type: Boolean +- Default value: `OFF` +- This variable controls whether to write statement summary records that are evicted by LRU to the statement summary log after [statements summary persistence](/statement-summary-tables.md#persist-statements-summary) is enabled. The written JSON records are marked with `"evicted": true` for downstream log consumers to identify. +- This variable takes effect only for the persistent implementation of statement summary. Records marked with `"evicted": true` are not returned as query results of `statements_summary_history` or `cluster_statements_summary_history`. +- After this variable is enabled, the amount of statement summary logs increases as LRU evictions become more frequent. Evicted records are written by using an asynchronous buffer mechanism. When the buffer queue is full, new evicted records might be dropped. + ### tidb_stmt_summary_refresh_interval New in v4.0 > **Note:** From b8ce27055ea3f9833f02fbd5f0cb1804781d6599 Mon Sep 17 00:00:00 2001 From: nolouch Date: Wed, 3 Jun 2026 13:23:28 -0700 Subject: [PATCH 02/10] docs: address statement summary review comments --- statement-summary-tables.md | 8 ++++---- system-variables.md | 12 ++++++------ 2 files changed, 10 insertions(+), 10 deletions(-) diff --git a/statement-summary-tables.md b/statement-summary-tables.md index ab203ac9f8e12..b2d09628b0ee8 100644 --- a/statement-summary-tables.md +++ b/statement-summary-tables.md @@ -88,7 +88,7 @@ The following is a sample output of querying `statements_summary`: > > - In TiDB, the time unit of fields in statement summary tables is nanosecond (ns), whereas in MySQL the time unit is picosecond (ps). > - Starting from v7.5.1 and v7.6.0, for clusters with [resource control](/tidb-resource-control-ru-groups.md) enabled, `statements_summary` will be aggregated by resource group, for example, the same statements executed in different resource groups will be collected as different records. -> - Starting from v8.5.7, you can use [`tidb_stmt_summary_group_by_user`](/system-variables.md#tidb_stmt_summary_group_by_user-new-in-v857) to control whether to further aggregate statement summaries by execution user. When the variable value is `ON`, the same SQL digest executed by different users is collected as different records, and the `SAMPLE_USER` field of each record indicates the execution user corresponding to the record. +> - Starting from v8.5.7, you can use [`tidb_stmt_summary_group_by_user`](/system-variables.md#tidb_stmt_summary_group_by_user-new-in-v857) to control whether to aggregate statement summaries by execution user. When this variable is set to `ON`, TiDB aggregates the same SQL digest executed by different users into separate records, and the `SAMPLE_USER` field of each record indicates the user who executed the statement. ## `statements_summary_history` @@ -146,8 +146,8 @@ The following system variables are used to control the statement summary: - `tidb_stmt_summary_max_sql_length`: Specifies the longest display length of `DIGEST_TEXT` and `QUERY_SAMPLE_TEXT`. The default value is `4096`. - `tidb_stmt_summary_internal_query`: Determines whether to count the TiDB SQL statements. `1` means to count, and `0` means not to count. The default value is `0`. -- `tidb_stmt_summary_group_by_user`: Determines whether to further aggregate statement summaries by execution user. `1` means to aggregate by user, and `0` means not to aggregate by user. The default value is `0`. After this variable is enabled, the same SQL digest executed by different users is aggregated into different rows, which might increase the number of statement summary records and memory usage. Modifying this variable clears the current in-memory statement summary data. -- `tidb_stmt_summary_persist_evicted`: Determines whether to write statement summary records that are evicted by LRU to the statement summary log after [statements summary persistence](#persist-statements-summary) is enabled. `1` means to write, and `0` means not to write. The default value is `0`. After this variable is enabled, the log contains JSON records marked with `"evicted": true`, and the amount of logs increases as LRU evictions become more frequent. +- `tidb_stmt_summary_group_by_user`: Determines whether to aggregate statement summaries by execution user. `1` means to aggregate by user, and `0` means not to aggregate by user. The default value is `0`. After you enable this variable, TiDB aggregates the same SQL digest executed by different users into separate rows, which might increase the number of statement summary records and memory usage. Modifying this variable clears the current in-memory statement summary data. +- `tidb_stmt_summary_persist_evicted`: Determines whether to write statement summary records evicted by LRU to the statement summary log after you enable [statements summary persistence](#persist-statements-summary). `1` means to write, and `0` means not to write. The default value is `0`. After you enable this variable, the log contains JSON records marked with `"evicted": true`, and the log volume increases as LRU evictions become more frequent. An example of the statement summary configuration is shown as follows: @@ -265,7 +265,7 @@ After statements summary persistence is enabled, the memory keeps only the curre > > - When statements summary persistence is enabled, the `tidb_stmt_summary_history_size` configuration described in the [Parameter configuration](#parameter-configuration) section will no longer take effect because the memory does not keep the history data. Instead, the following three configurations will be used to control the retention period and size of history data for persistence: [`tidb_stmt_summary_file_max_days`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_days-new-in-v660), [`tidb_stmt_summary_file_max_size`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_size-new-in-v660), and [`tidb_stmt_summary_file_max_backups`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_backups-new-in-v660). > - The smaller the value of `tidb_stmt_summary_refresh_interval`, the more immediate data is written to the disk. However, this also means more redundant data is written to the disk. -> - Starting from v8.5.7, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. The written JSON records are marked with `"evicted": true` for downstream log consumers to identify and are not returned as query results of `statements_summary_history` or `cluster_statements_summary_history`. +> - Starting from v8.5.7, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. TiDB marks these JSON records with `"evicted": true` for downstream log consumers to identify. TiDB does not return these records as query results of `statements_summary_history` or `cluster_statements_summary_history`. diff --git a/system-variables.md b/system-variables.md index 22e9e628866ac..a346c2adff68a 100644 --- a/system-variables.md +++ b/system-variables.md @@ -6337,9 +6337,9 @@ For details, see [Identify Slow Queries](/identify-slow-queries.md). - Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No - Type: Boolean - Default value: `OFF` -- This variable controls whether to include the user that executes SQL statements as an aggregation dimension in [statement summary tables](/statement-summary-tables.md). When the variable value is `OFF`, the same SQL digest executed by different users is aggregated into the same row, and the `SAMPLE_USER` field displays one sampled user. When the variable value is `ON`, the same SQL digest executed by different users is aggregated into different rows, and the `SAMPLE_USER` field of each row indicates the execution user corresponding to the row. -- Modifying this variable clears the current in-memory statement summary data because data before and after the modification uses different aggregation dimensions. Historical data that has been persisted to the disk is not affected. -- After this variable is enabled, the number of statement summary records might increase with the number of different execution users for the same SQL digest, which increases memory usage. +- This variable controls whether to include the user who executes SQL statements as an aggregation dimension in [statement summary tables](/statement-summary-tables.md). When this variable is set to `OFF`, TiDB aggregates the same SQL digest executed by different users into the same row, and the `SAMPLE_USER` field displays one sampled user. When this variable is set to `ON`, TiDB aggregates the same SQL digest executed by different users into separate rows, and the `SAMPLE_USER` field of each row indicates the user who executed the statement. +- Modifying this variable clears the current in-memory statement summary data because data before and after the modification uses different aggregation dimensions. This does not affect historical data persisted to the disk. +- After you enable this variable, the number of statement summary records might increase with the number of different execution users for the same SQL digest, which increases memory usage. ### tidb_stmt_summary_history_size New in v4.0 @@ -6423,9 +6423,9 @@ For details, see [Identify Slow Queries](/identify-slow-queries.md). - Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No - Type: Boolean - Default value: `OFF` -- This variable controls whether to write statement summary records that are evicted by LRU to the statement summary log after [statements summary persistence](/statement-summary-tables.md#persist-statements-summary) is enabled. The written JSON records are marked with `"evicted": true` for downstream log consumers to identify. -- This variable takes effect only for the persistent implementation of statement summary. Records marked with `"evicted": true` are not returned as query results of `statements_summary_history` or `cluster_statements_summary_history`. -- After this variable is enabled, the amount of statement summary logs increases as LRU evictions become more frequent. Evicted records are written by using an asynchronous buffer mechanism. When the buffer queue is full, new evicted records might be dropped. +- This variable controls whether to write statement summary records evicted by LRU to the statement summary log after you enable [statements summary persistence](/statement-summary-tables.md#persist-statements-summary). TiDB marks these JSON records with `"evicted": true` for downstream log consumers to identify. +- This variable takes effect only for the persistent implementation of statement summary. TiDB does not return records marked with `"evicted": true` as query results of `statements_summary_history` or `cluster_statements_summary_history`. +- After you enable this variable, the log volume increases as LRU evictions become more frequent. TiDB writes evicted records using an asynchronous buffer mechanism. When the buffer queue is full, TiDB might drop new evicted records. ### tidb_stmt_summary_refresh_interval New in v4.0 From 7c8957bd239a1c5304afd8e971f7bab5aa459176 Mon Sep 17 00:00:00 2001 From: Grace Cai Date: Fri, 21 Aug 2026 14:18:03 +0800 Subject: [PATCH 03/10] Apply suggestions from code review --- statement-summary-tables.md | 4 ++-- system-variables.md | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/statement-summary-tables.md b/statement-summary-tables.md index b2d09628b0ee8..594363348141e 100644 --- a/statement-summary-tables.md +++ b/statement-summary-tables.md @@ -88,7 +88,7 @@ The following is a sample output of querying `statements_summary`: > > - In TiDB, the time unit of fields in statement summary tables is nanosecond (ns), whereas in MySQL the time unit is picosecond (ps). > - Starting from v7.5.1 and v7.6.0, for clusters with [resource control](/tidb-resource-control-ru-groups.md) enabled, `statements_summary` will be aggregated by resource group, for example, the same statements executed in different resource groups will be collected as different records. -> - Starting from v8.5.7, you can use [`tidb_stmt_summary_group_by_user`](/system-variables.md#tidb_stmt_summary_group_by_user-new-in-v857) to control whether to aggregate statement summaries by execution user. When this variable is set to `ON`, TiDB aggregates the same SQL digest executed by different users into separate records, and the `SAMPLE_USER` field of each record indicates the user who executed the statement. +> - Starting from TiDB-X-CLOUD.202603.1 you can use [`tidb_stmt_summary_group_by_user`](/system-variables.md#tidb_stmt_summary_group_by_user-new-in-v857) to control whether to aggregate statement summaries by execution user. When this variable is set to `ON`, TiDB aggregates the same SQL digest executed by different users into separate records, and the `SAMPLE_USER` field of each record indicates the user who executed the statement. ## `statements_summary_history` @@ -265,7 +265,7 @@ After statements summary persistence is enabled, the memory keeps only the curre > > - When statements summary persistence is enabled, the `tidb_stmt_summary_history_size` configuration described in the [Parameter configuration](#parameter-configuration) section will no longer take effect because the memory does not keep the history data. Instead, the following three configurations will be used to control the retention period and size of history data for persistence: [`tidb_stmt_summary_file_max_days`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_days-new-in-v660), [`tidb_stmt_summary_file_max_size`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_size-new-in-v660), and [`tidb_stmt_summary_file_max_backups`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_backups-new-in-v660). > - The smaller the value of `tidb_stmt_summary_refresh_interval`, the more immediate data is written to the disk. However, this also means more redundant data is written to the disk. -> - Starting from v8.5.7, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. TiDB marks these JSON records with `"evicted": true` for downstream log consumers to identify. TiDB does not return these records as query results of `statements_summary_history` or `cluster_statements_summary_history`. +> - Starting from TiDB-X-CLOUD.202603.1, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. TiDB marks these JSON records with `"evicted": true` for downstream log consumers to identify. TiDB does not return these records as query results of `statements_summary_history` or `cluster_statements_summary_history`. diff --git a/system-variables.md b/system-variables.md index a346c2adff68a..538093ff7e1d1 100644 --- a/system-variables.md +++ b/system-variables.md @@ -6330,7 +6330,7 @@ For details, see [Identify Slow Queries](/identify-slow-queries.md). -### tidb_stmt_summary_group_by_user New in v8.5.7 +### tidb_stmt_summary_group_by_user TiDB-X-CLOUD.202603.1 - Scope: GLOBAL - Persists to cluster: Yes @@ -6416,7 +6416,7 @@ For details, see [Identify Slow Queries](/identify-slow-queries.md). -### tidb_stmt_summary_persist_evicted New in v8.5.7 +### tidb_stmt_summary_persist_evicted New in TiDB-X-CLOUD.202603.1 - Scope: GLOBAL - Persists to cluster: Yes From a78ae6bc1da1acf46b8d31f39e289411182a5e96 Mon Sep 17 00:00:00 2001 From: Grace Cai Date: Mon, 31 Aug 2026 16:38:24 +0800 Subject: [PATCH 04/10] Apply suggestions from code review --- system-variables.md | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/system-variables.md b/system-variables.md index 538093ff7e1d1..09cdca9ea8a1b 100644 --- a/system-variables.md +++ b/system-variables.md @@ -6330,7 +6330,12 @@ For details, see [Identify Slow Queries](/identify-slow-queries.md). -### tidb_stmt_summary_group_by_user TiDB-X-CLOUD.202603.1 +### tidb_stmt_summary_group_by_user New in v9.0.0 and TiDB-X-CLOUD.202603 + +> **Note:** +> +> - For TiDB Cloud Starter, this variable is not supported. +> - For TiDB Cloud Essential and Premium, this variable is read-only. - Scope: GLOBAL - Persists to cluster: Yes @@ -6416,7 +6421,12 @@ For details, see [Identify Slow Queries](/identify-slow-queries.md). -### tidb_stmt_summary_persist_evicted New in TiDB-X-CLOUD.202603.1 +### tidb_stmt_summary_persist_evicted New in v9.0.0 and TiDB-X-CLOUD.202603 + +> **Note:** +> +> - For TiDB Cloud Starter, this variable is not supported. +> - For TiDB Cloud Essential and Premium, this variable is read-only. - Scope: GLOBAL - Persists to cluster: Yes From 82ba6739d91f9487b48be1408067afd405924838 Mon Sep 17 00:00:00 2001 From: Grace Cai Date: Mon, 31 Aug 2026 16:41:06 +0800 Subject: [PATCH 05/10] Apply suggestions from code review --- statement-summary-tables.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/statement-summary-tables.md b/statement-summary-tables.md index 594363348141e..ebbad8c72cb39 100644 --- a/statement-summary-tables.md +++ b/statement-summary-tables.md @@ -88,7 +88,7 @@ The following is a sample output of querying `statements_summary`: > > - In TiDB, the time unit of fields in statement summary tables is nanosecond (ns), whereas in MySQL the time unit is picosecond (ps). > - Starting from v7.5.1 and v7.6.0, for clusters with [resource control](/tidb-resource-control-ru-groups.md) enabled, `statements_summary` will be aggregated by resource group, for example, the same statements executed in different resource groups will be collected as different records. -> - Starting from TiDB-X-CLOUD.202603.1 you can use [`tidb_stmt_summary_group_by_user`](/system-variables.md#tidb_stmt_summary_group_by_user-new-in-v857) to control whether to aggregate statement summaries by execution user. When this variable is set to `ON`, TiDB aggregates the same SQL digest executed by different users into separate records, and the `SAMPLE_USER` field of each record indicates the user who executed the statement. +> - For TiDB Self-Managed, starting from v9.0.0, you can use [`tidb_stmt_summary_group_by_user`](/system-variables.md#tidb_stmt_summary_group_by_user-new-in-v857) to control whether to aggregate statement summaries by execution user. When this variable is set to `ON`, TiDB aggregates the same SQL digest executed by different users into separate records, and the `SAMPLE_USER` field of each record indicates the user who executed the statement. ## `statements_summary_history` @@ -265,7 +265,7 @@ After statements summary persistence is enabled, the memory keeps only the curre > > - When statements summary persistence is enabled, the `tidb_stmt_summary_history_size` configuration described in the [Parameter configuration](#parameter-configuration) section will no longer take effect because the memory does not keep the history data. Instead, the following three configurations will be used to control the retention period and size of history data for persistence: [`tidb_stmt_summary_file_max_days`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_days-new-in-v660), [`tidb_stmt_summary_file_max_size`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_size-new-in-v660), and [`tidb_stmt_summary_file_max_backups`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_backups-new-in-v660). > - The smaller the value of `tidb_stmt_summary_refresh_interval`, the more immediate data is written to the disk. However, this also means more redundant data is written to the disk. -> - Starting from TiDB-X-CLOUD.202603.1, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. TiDB marks these JSON records with `"evicted": true` for downstream log consumers to identify. TiDB does not return these records as query results of `statements_summary_history` or `cluster_statements_summary_history`. +> - For TiDB Self-Managed, starting from v9.0.0, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. TiDB marks these JSON records with `"evicted": true` for downstream log consumers to identify. TiDB does not return these records as query results of `statements_summary_history` or `cluster_statements_summary_history`. From 8f037c64a86ca1c94264787941dee214a97f8564 Mon Sep 17 00:00:00 2001 From: Grace Cai Date: Mon, 31 Aug 2026 16:50:40 +0800 Subject: [PATCH 06/10] Apply suggestions from code review --- statement-summary-tables.md | 4 ++-- system-variables.md | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/statement-summary-tables.md b/statement-summary-tables.md index ebbad8c72cb39..e2efef6dcbe6d 100644 --- a/statement-summary-tables.md +++ b/statement-summary-tables.md @@ -88,7 +88,7 @@ The following is a sample output of querying `statements_summary`: > > - In TiDB, the time unit of fields in statement summary tables is nanosecond (ns), whereas in MySQL the time unit is picosecond (ps). > - Starting from v7.5.1 and v7.6.0, for clusters with [resource control](/tidb-resource-control-ru-groups.md) enabled, `statements_summary` will be aggregated by resource group, for example, the same statements executed in different resource groups will be collected as different records. -> - For TiDB Self-Managed, starting from v9.0.0, you can use [`tidb_stmt_summary_group_by_user`](/system-variables.md#tidb_stmt_summary_group_by_user-new-in-v857) to control whether to aggregate statement summaries by execution user. When this variable is set to `ON`, TiDB aggregates the same SQL digest executed by different users into separate records, and the `SAMPLE_USER` field of each record indicates the user who executed the statement. +> - For TiDB Self-Managed, starting from v9.0.0, you can use [`tidb_stmt_summary_group_by_user`](/system-variables.md#tidb_stmt_summary_group_by_user-new-in-v857) to control whether to aggregate statement summaries by execution user. When this variable is set to `ON`, TiDB aggregates the same SQL digest executed by different users into separate records, and the `SAMPLE_USER` field of each record indicates the user who executed the statement. For TiDB Cloud Essential and Premium, `tidb_stmt_summary_group_by_user` is read-only. If you need to modify it, contact [TiDB Cloud Support](/tidb-cloud/tidb-cloud-support.md). ## `statements_summary_history` @@ -265,7 +265,7 @@ After statements summary persistence is enabled, the memory keeps only the curre > > - When statements summary persistence is enabled, the `tidb_stmt_summary_history_size` configuration described in the [Parameter configuration](#parameter-configuration) section will no longer take effect because the memory does not keep the history data. Instead, the following three configurations will be used to control the retention period and size of history data for persistence: [`tidb_stmt_summary_file_max_days`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_days-new-in-v660), [`tidb_stmt_summary_file_max_size`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_size-new-in-v660), and [`tidb_stmt_summary_file_max_backups`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_backups-new-in-v660). > - The smaller the value of `tidb_stmt_summary_refresh_interval`, the more immediate data is written to the disk. However, this also means more redundant data is written to the disk. -> - For TiDB Self-Managed, starting from v9.0.0, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. TiDB marks these JSON records with `"evicted": true` for downstream log consumers to identify. TiDB does not return these records as query results of `statements_summary_history` or `cluster_statements_summary_history`. +> - For TiDB Self-Managed, starting from v9.0.0, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. TiDB marks these JSON records with `"evicted": true` for downstream log consumers to identify. TiDB does not return these records as query results of `statements_summary_history` or `cluster_statements_summary_history`. For TiDB Cloud Essential and Premium, `tidb_stmt_summary_group_by_user` is read-only. If you need to modify it, contact [TiDB Cloud Support](/tidb-cloud/tidb-cloud-support.md). diff --git a/system-variables.md b/system-variables.md index 09cdca9ea8a1b..5b260ebfe90b0 100644 --- a/system-variables.md +++ b/system-variables.md @@ -6335,7 +6335,7 @@ For details, see [Identify Slow Queries](/identify-slow-queries.md). > **Note:** > > - For TiDB Cloud Starter, this variable is not supported. -> - For TiDB Cloud Essential and Premium, this variable is read-only. +> - For TiDB Cloud Essential and Premium, this variable is read-only. If you need to modify it, contact [TiDB Cloud Support](https://docs.pingcap.com/tidbcloud/tidb-cloud-support/). - Scope: GLOBAL - Persists to cluster: Yes @@ -6426,7 +6426,7 @@ For details, see [Identify Slow Queries](/identify-slow-queries.md). > **Note:** > > - For TiDB Cloud Starter, this variable is not supported. -> - For TiDB Cloud Essential and Premium, this variable is read-only. +> - For TiDB Cloud Essential and Premium, this variable is read-only. If you need to modify it, contact [TiDB Cloud Support](https://docs.pingcap.com/tidbcloud/tidb-cloud-support/). - Scope: GLOBAL - Persists to cluster: Yes From 596b289437d634ca239fc47bcfd0455c524cb408 Mon Sep 17 00:00:00 2001 From: Grace Cai Date: Mon, 31 Aug 2026 16:51:49 +0800 Subject: [PATCH 07/10] Apply suggestions from code review --- statement-summary-tables.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/statement-summary-tables.md b/statement-summary-tables.md index e2efef6dcbe6d..1c78e1dd74ea8 100644 --- a/statement-summary-tables.md +++ b/statement-summary-tables.md @@ -88,7 +88,7 @@ The following is a sample output of querying `statements_summary`: > > - In TiDB, the time unit of fields in statement summary tables is nanosecond (ns), whereas in MySQL the time unit is picosecond (ps). > - Starting from v7.5.1 and v7.6.0, for clusters with [resource control](/tidb-resource-control-ru-groups.md) enabled, `statements_summary` will be aggregated by resource group, for example, the same statements executed in different resource groups will be collected as different records. -> - For TiDB Self-Managed, starting from v9.0.0, you can use [`tidb_stmt_summary_group_by_user`](/system-variables.md#tidb_stmt_summary_group_by_user-new-in-v857) to control whether to aggregate statement summaries by execution user. When this variable is set to `ON`, TiDB aggregates the same SQL digest executed by different users into separate records, and the `SAMPLE_USER` field of each record indicates the user who executed the statement. For TiDB Cloud Essential and Premium, `tidb_stmt_summary_group_by_user` is read-only. If you need to modify it, contact [TiDB Cloud Support](/tidb-cloud/tidb-cloud-support.md). +> - For TiDB Self-Managed, starting from v9.0.0, you can use [`tidb_stmt_summary_group_by_user`](/system-variables.md#tidb_stmt_summary_group_by_user-new-in-v857) to control whether to aggregate statement summaries by execution user. When this variable is set to `ON`, TiDB aggregates the same SQL digest executed by different users into separate records, and the `SAMPLE_USER` field of each record indicates the user who executed the statement. For TiDB Cloud Essential and Premium, `tidb_stmt_summary_group_by_user` is read-only. If you need to modify it, contact [TiDB Cloud Support](https://docs.pingcap.com/tidbcloud/tidb-cloud-support/). ## `statements_summary_history` @@ -265,7 +265,7 @@ After statements summary persistence is enabled, the memory keeps only the curre > > - When statements summary persistence is enabled, the `tidb_stmt_summary_history_size` configuration described in the [Parameter configuration](#parameter-configuration) section will no longer take effect because the memory does not keep the history data. Instead, the following three configurations will be used to control the retention period and size of history data for persistence: [`tidb_stmt_summary_file_max_days`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_days-new-in-v660), [`tidb_stmt_summary_file_max_size`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_size-new-in-v660), and [`tidb_stmt_summary_file_max_backups`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_backups-new-in-v660). > - The smaller the value of `tidb_stmt_summary_refresh_interval`, the more immediate data is written to the disk. However, this also means more redundant data is written to the disk. -> - For TiDB Self-Managed, starting from v9.0.0, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. TiDB marks these JSON records with `"evicted": true` for downstream log consumers to identify. TiDB does not return these records as query results of `statements_summary_history` or `cluster_statements_summary_history`. For TiDB Cloud Essential and Premium, `tidb_stmt_summary_group_by_user` is read-only. If you need to modify it, contact [TiDB Cloud Support](/tidb-cloud/tidb-cloud-support.md). +> - For TiDB Self-Managed, starting from v9.0.0, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. TiDB marks these JSON records with `"evicted": true` for downstream log consumers to identify. TiDB does not return these records as query results of `statements_summary_history` or `cluster_statements_summary_history`. For TiDB Cloud Essential and Premium, `tidb_stmt_summary_group_by_user` is read-only. If you need to modify it, contact [TiDB Cloud Support](https://docs.pingcap.com/tidbcloud/tidb-cloud-support/). From eb399054a718ae4e41eb1a1d9ad233fdacca432e Mon Sep 17 00:00:00 2001 From: Grace Cai Date: Mon, 31 Aug 2026 16:52:59 +0800 Subject: [PATCH 08/10] Apply suggestions from code review --- statement-summary-tables.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/statement-summary-tables.md b/statement-summary-tables.md index 1c78e1dd74ea8..220ca0b67bfd9 100644 --- a/statement-summary-tables.md +++ b/statement-summary-tables.md @@ -88,7 +88,7 @@ The following is a sample output of querying `statements_summary`: > > - In TiDB, the time unit of fields in statement summary tables is nanosecond (ns), whereas in MySQL the time unit is picosecond (ps). > - Starting from v7.5.1 and v7.6.0, for clusters with [resource control](/tidb-resource-control-ru-groups.md) enabled, `statements_summary` will be aggregated by resource group, for example, the same statements executed in different resource groups will be collected as different records. -> - For TiDB Self-Managed, starting from v9.0.0, you can use [`tidb_stmt_summary_group_by_user`](/system-variables.md#tidb_stmt_summary_group_by_user-new-in-v857) to control whether to aggregate statement summaries by execution user. When this variable is set to `ON`, TiDB aggregates the same SQL digest executed by different users into separate records, and the `SAMPLE_USER` field of each record indicates the user who executed the statement. For TiDB Cloud Essential and Premium, `tidb_stmt_summary_group_by_user` is read-only. If you need to modify it, contact [TiDB Cloud Support](https://docs.pingcap.com/tidbcloud/tidb-cloud-support/). +> - For TiDB Self-Managed, starting from v9.0.0, you can use [`tidb_stmt_summary_group_by_user`](/system-variables.md#tidb_stmt_summary_group_by_user-new-in-v857) to control whether to aggregate statement summaries by execution user. When this variable is set to `ON`, TiDB aggregates the same SQL digest executed by different users into separate records, and the `SAMPLE_USER` field of each record indicates the user who executed the statement. For TiDB Cloud Essential and Premium, `tidb_stmt_summary_group_by_user` is read-only. If you need to modify it, contact [TiDB Cloud Support](https://docs.pingcap.com/tidbcloud/tidb-cloud-support/). ## `statements_summary_history` @@ -265,7 +265,7 @@ After statements summary persistence is enabled, the memory keeps only the curre > > - When statements summary persistence is enabled, the `tidb_stmt_summary_history_size` configuration described in the [Parameter configuration](#parameter-configuration) section will no longer take effect because the memory does not keep the history data. Instead, the following three configurations will be used to control the retention period and size of history data for persistence: [`tidb_stmt_summary_file_max_days`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_days-new-in-v660), [`tidb_stmt_summary_file_max_size`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_size-new-in-v660), and [`tidb_stmt_summary_file_max_backups`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_backups-new-in-v660). > - The smaller the value of `tidb_stmt_summary_refresh_interval`, the more immediate data is written to the disk. However, this also means more redundant data is written to the disk. -> - For TiDB Self-Managed, starting from v9.0.0, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. TiDB marks these JSON records with `"evicted": true` for downstream log consumers to identify. TiDB does not return these records as query results of `statements_summary_history` or `cluster_statements_summary_history`. For TiDB Cloud Essential and Premium, `tidb_stmt_summary_group_by_user` is read-only. If you need to modify it, contact [TiDB Cloud Support](https://docs.pingcap.com/tidbcloud/tidb-cloud-support/). +> - For TiDB Self-Managed, starting from v9.0.0, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. TiDB marks these JSON records with `"evicted": true` for downstream log consumers to identify. TiDB does not return these records as query results of `statements_summary_history` or `cluster_statements_summary_history`. For TiDB Cloud Essential and Premium, `tidb_stmt_summary_group_by_user` is read-only. If you need to modify it, contact [TiDB Cloud Support](https://docs.pingcap.com/tidbcloud/tidb-cloud-support/). From 8f92301fa61044014546cb67b7487351fa8f2cd4 Mon Sep 17 00:00:00 2001 From: qiancai Date: Mon, 31 Aug 2026 17:00:16 +0800 Subject: [PATCH 09/10] Update statement-summary-tables.md --- statement-summary-tables.md | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/statement-summary-tables.md b/statement-summary-tables.md index 220ca0b67bfd9..fc6d50ac8c127 100644 --- a/statement-summary-tables.md +++ b/statement-summary-tables.md @@ -265,10 +265,13 @@ After statements summary persistence is enabled, the memory keeps only the curre > > - When statements summary persistence is enabled, the `tidb_stmt_summary_history_size` configuration described in the [Parameter configuration](#parameter-configuration) section will no longer take effect because the memory does not keep the history data. Instead, the following three configurations will be used to control the retention period and size of history data for persistence: [`tidb_stmt_summary_file_max_days`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_days-new-in-v660), [`tidb_stmt_summary_file_max_size`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_size-new-in-v660), and [`tidb_stmt_summary_file_max_backups`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_backups-new-in-v660). > - The smaller the value of `tidb_stmt_summary_refresh_interval`, the more immediate data is written to the disk. However, this also means more redundant data is written to the disk. -> - For TiDB Self-Managed, starting from v9.0.0, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. TiDB marks these JSON records with `"evicted": true` for downstream log consumers to identify. TiDB does not return these records as query results of `statements_summary_history` or `cluster_statements_summary_history`. For TiDB Cloud Essential and Premium, `tidb_stmt_summary_group_by_user` is read-only. If you need to modify it, contact [TiDB Cloud Support](https://docs.pingcap.com/tidbcloud/tidb-cloud-support/). +> **Note:** +> +> For TiDB Self-Managed, starting from v9.0.0, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. TiDB marks these JSON records with `"evicted": true` for downstream log consumers to identify. TiDB does not return these records as query results of `statements_summary_history` or `cluster_statements_summary_history`. For TiDB Cloud Essential and Premium, `tidb_stmt_summary_group_by_user` is read-only. If you need to modify it, contact [TiDB Cloud Support](https://docs.pingcap.com/tidbcloud/tidb-cloud-support/). + ## Troubleshooting examples This section provides two examples to show how to use the statement summary feature to troubleshoot SQL performance issues. From c8e852a71b8330e8b8f84aa138e27fcf086cbb76 Mon Sep 17 00:00:00 2001 From: Grace Cai Date: Mon, 31 Aug 2026 17:52:46 +0800 Subject: [PATCH 10/10] Apply suggestions from code review --- statement-summary-tables.md | 4 ++-- system-variables.md | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/statement-summary-tables.md b/statement-summary-tables.md index fc6d50ac8c127..fc8edd434f6a9 100644 --- a/statement-summary-tables.md +++ b/statement-summary-tables.md @@ -88,7 +88,7 @@ The following is a sample output of querying `statements_summary`: > > - In TiDB, the time unit of fields in statement summary tables is nanosecond (ns), whereas in MySQL the time unit is picosecond (ps). > - Starting from v7.5.1 and v7.6.0, for clusters with [resource control](/tidb-resource-control-ru-groups.md) enabled, `statements_summary` will be aggregated by resource group, for example, the same statements executed in different resource groups will be collected as different records. -> - For TiDB Self-Managed, starting from v9.0.0, you can use [`tidb_stmt_summary_group_by_user`](/system-variables.md#tidb_stmt_summary_group_by_user-new-in-v857) to control whether to aggregate statement summaries by execution user. When this variable is set to `ON`, TiDB aggregates the same SQL digest executed by different users into separate records, and the `SAMPLE_USER` field of each record indicates the user who executed the statement. For TiDB Cloud Essential and Premium, `tidb_stmt_summary_group_by_user` is read-only. If you need to modify it, contact [TiDB Cloud Support](https://docs.pingcap.com/tidbcloud/tidb-cloud-support/). +> - For TiDB Self-Managed, starting from v9.0.0, you can use [`tidb_stmt_summary_group_by_user`](/system-variables.md#tidb_stmt_summary_group_by_user-new-in-v857) to control whether to aggregate statement summaries by execution user. When this variable is set to `ON`, TiDB aggregates the same SQL digest executed by different users into separate records, and the `SAMPLE_USER` field of each record indicates the user who executed the statement. For TiDB Cloud Essential and Premium, `tidb_stmt_summary_group_by_user` is read-only. ## `statements_summary_history` @@ -270,7 +270,7 @@ After statements summary persistence is enabled, the memory keeps only the curre > **Note:** > -> For TiDB Self-Managed, starting from v9.0.0, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. TiDB marks these JSON records with `"evicted": true` for downstream log consumers to identify. TiDB does not return these records as query results of `statements_summary_history` or `cluster_statements_summary_history`. For TiDB Cloud Essential and Premium, `tidb_stmt_summary_group_by_user` is read-only. If you need to modify it, contact [TiDB Cloud Support](https://docs.pingcap.com/tidbcloud/tidb-cloud-support/). +> For TiDB Self-Managed, starting from v9.0.0, you can enable [`tidb_stmt_summary_persist_evicted`](/system-variables.md#tidb_stmt_summary_persist_evicted-new-in-v857) to write records evicted by LRU to the statement summary log. TiDB marks these JSON records with `"evicted": true` for downstream log consumers to identify. TiDB does not return these records as query results of `statements_summary_history` or `cluster_statements_summary_history`. For TiDB Cloud Essential and Premium, `tidb_stmt_summary_group_by_user` is read-only. ## Troubleshooting examples diff --git a/system-variables.md b/system-variables.md index 5b260ebfe90b0..09cdca9ea8a1b 100644 --- a/system-variables.md +++ b/system-variables.md @@ -6335,7 +6335,7 @@ For details, see [Identify Slow Queries](/identify-slow-queries.md). > **Note:** > > - For TiDB Cloud Starter, this variable is not supported. -> - For TiDB Cloud Essential and Premium, this variable is read-only. If you need to modify it, contact [TiDB Cloud Support](https://docs.pingcap.com/tidbcloud/tidb-cloud-support/). +> - For TiDB Cloud Essential and Premium, this variable is read-only. - Scope: GLOBAL - Persists to cluster: Yes @@ -6426,7 +6426,7 @@ For details, see [Identify Slow Queries](/identify-slow-queries.md). > **Note:** > > - For TiDB Cloud Starter, this variable is not supported. -> - For TiDB Cloud Essential and Premium, this variable is read-only. If you need to modify it, contact [TiDB Cloud Support](https://docs.pingcap.com/tidbcloud/tidb-cloud-support/). +> - For TiDB Cloud Essential and Premium, this variable is read-only. - Scope: GLOBAL - Persists to cluster: Yes