From 764e61c1a00c6d6bfad3d28fa15b13a9b5230c3a Mon Sep 17 00:00:00 2001 From: Jianjun Liao Date: Thu, 31 Jul 2025 13:50:28 +0800 Subject: [PATCH 1/5] draft Signed-off-by: Jianjun Liao --- system-variables.md | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/system-variables.md b/system-variables.md index 6d1e2fd125559..701c8f9f7e30b 100644 --- a/system-variables.md +++ b/system-variables.md @@ -1043,6 +1043,16 @@ mysql> SHOW GLOBAL VARIABLES LIKE 'max_prepared_stmt_count'; - Unit: Bytes - This variable is used to control the threshold at which the TiDB server prefers to send read requests to a replica in the same availability zone as the TiDB server when [`tidb_replica_read`](#tidb_replica_read-new-in-v40) is set to `closest-adaptive`. If the estimated result is higher than or equal to this threshold, TiDB prefers to send read requests to a replica in the same availability zone. Otherwise, TiDB sends read requests to the leader replica. +### tidb_advancer_check_point_lag_limit New in v9.1.0 + +- Scope: GLOBAL +- Persists to cluster: Yes +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No +- Type: Duration +- Default value: `48h0m0s` +- Range: `[1s, 8760h0m0s]` +- This variable is used to control the lag time limit of the log backup task checkpoint. If the checkpoint lag of the log backup task exceeds this limit, the task will be paused by TiDB Advancer. + ### tidb_allow_tiflash_cop New in v7.3.0 - Scope: SESSION | GLOBAL From 882c00221d8563891cca3a6a3af6713e1d3e0c7c Mon Sep 17 00:00:00 2001 From: Jianjun Liao <36503113+Leavrth@users.noreply.github.com> Date: Tue, 5 Aug 2025 11:35:56 +0800 Subject: [PATCH 2/5] Update system-variables.md --- system-variables.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/system-variables.md b/system-variables.md index 701c8f9f7e30b..9f3cba114ddc2 100644 --- a/system-variables.md +++ b/system-variables.md @@ -1043,7 +1043,7 @@ mysql> SHOW GLOBAL VARIABLES LIKE 'max_prepared_stmt_count'; - Unit: Bytes - This variable is used to control the threshold at which the TiDB server prefers to send read requests to a replica in the same availability zone as the TiDB server when [`tidb_replica_read`](#tidb_replica_read-new-in-v40) is set to `closest-adaptive`. If the estimated result is higher than or equal to this threshold, TiDB prefers to send read requests to a replica in the same availability zone. Otherwise, TiDB sends read requests to the leader replica. -### tidb_advancer_check_point_lag_limit New in v9.1.0 +### tidb_advancer_check_point_lag_limit New in v9.0.0 - Scope: GLOBAL - Persists to cluster: Yes From d57201b7d1c0e8e9e70117b993af2b9a026abca1 Mon Sep 17 00:00:00 2001 From: xixirangrang Date: Tue, 5 Aug 2025 12:06:13 +0800 Subject: [PATCH 3/5] Update system-variables.md Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com> --- system-variables.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/system-variables.md b/system-variables.md index 9f3cba114ddc2..fc6530a1d021f 100644 --- a/system-variables.md +++ b/system-variables.md @@ -1051,7 +1051,7 @@ mysql> SHOW GLOBAL VARIABLES LIKE 'max_prepared_stmt_count'; - Type: Duration - Default value: `48h0m0s` - Range: `[1s, 8760h0m0s]` -- This variable is used to control the lag time limit of the log backup task checkpoint. If the checkpoint lag of the log backup task exceeds this limit, the task will be paused by TiDB Advancer. +- This variable is used to control the maximum allowed checkpoint lag for a log backup task. If a task's checkpoint lag exceeds this limit, TiDB Advancer pauses the task. ### tidb_allow_tiflash_cop New in v7.3.0 From 73a68f1ba01536a188443b6192b60f6b9bba08c3 Mon Sep 17 00:00:00 2001 From: xixirangrang Date: Thu, 25 Dec 2025 11:56:15 +0800 Subject: [PATCH 4/5] Update system-variables.md --- system-variables.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/system-variables.md b/system-variables.md index fc6530a1d021f..610a178ad599b 100644 --- a/system-variables.md +++ b/system-variables.md @@ -1043,7 +1043,7 @@ mysql> SHOW GLOBAL VARIABLES LIKE 'max_prepared_stmt_count'; - Unit: Bytes - This variable is used to control the threshold at which the TiDB server prefers to send read requests to a replica in the same availability zone as the TiDB server when [`tidb_replica_read`](#tidb_replica_read-new-in-v40) is set to `closest-adaptive`. If the estimated result is higher than or equal to this threshold, TiDB prefers to send read requests to a replica in the same availability zone. Otherwise, TiDB sends read requests to the leader replica. -### tidb_advancer_check_point_lag_limit New in v9.0.0 +### tidb_advancer_check_point_lag_limit New in v8.5.5 and v9.0.0 - Scope: GLOBAL - Persists to cluster: Yes From 79b1d427c561ce4979d089f0e0079821acaa47c4 Mon Sep 17 00:00:00 2001 From: Lilian Lee Date: Thu, 25 Dec 2025 17:54:51 +0800 Subject: [PATCH 5/5] Simplify wording --- system-variables.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/system-variables.md b/system-variables.md index 610a178ad599b..781ac0156d266 100644 --- a/system-variables.md +++ b/system-variables.md @@ -1051,7 +1051,7 @@ mysql> SHOW GLOBAL VARIABLES LIKE 'max_prepared_stmt_count'; - Type: Duration - Default value: `48h0m0s` - Range: `[1s, 8760h0m0s]` -- This variable is used to control the maximum allowed checkpoint lag for a log backup task. If a task's checkpoint lag exceeds this limit, TiDB Advancer pauses the task. +- This variable controls the maximum allowed checkpoint lag for a log backup task. If a task's checkpoint lag exceeds this limit, TiDB Advancer pauses the task. ### tidb_allow_tiflash_cop New in v7.3.0