From 2f1a089c0c2076e3c69707d5b5b3764680422bef Mon Sep 17 00:00:00 2001 From: ti-srebot <66930949+ti-srebot@users.noreply.github.com> Date: Tue, 14 Jul 2020 16:50:50 +0800 Subject: [PATCH] add distinct-agg-push-down in tidb config file (#3259) (#3266) * cherry pick #3259 to release-4.0 Signed-off-by: ti-srebot * resolve conflict * resolve conflict Co-authored-by: Ran --- system-variables.md | 3 +-- tidb-configuration-file.md | 12 ++++++++++++ 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/system-variables.md b/system-variables.md index da19319ffae3f..bb78476afbc5c 100644 --- a/system-variables.md +++ b/system-variables.md @@ -1,8 +1,7 @@ --- title: System Variables summary: Use system variables to optimize performance or alter running behavior. -category: reference -aliases: ['/tidb/stable/tidb-specific-system-variables','/docs/stable/system-variables/','/docs/v4.0/system-variables/','/docs/stable/reference/configuration/tidb-server/mysql-variables/','/docs/stable/tidb-specific-system-variables/','/docs/v4.0/tidb-specific-system-variables/','/docs/stable/reference/configuration/tidb-server/tidb-specific-variables/'] +aliases: ['/tidb/stable/tidb-specific-system-variables','/docs/stable/system-variables/','/docs/v4.0/system-variables/','/docs/stable/reference/configuration/tidb-server/mysql-variables/','/docs/stable/tidb-specific-system-variables/','/docs/v4.0/tidb-specific-system-variables/','/docs/stable/reference/configuration/tidb-server/tidb-specific-variables/','/tidb/stable/tidb-specific-system-variables'] --- # System Variables diff --git a/tidb-configuration-file.md b/tidb-configuration-file.md index b2db8d9a80cdb..b91834969a92b 100644 --- a/tidb-configuration-file.md +++ b/tidb-configuration-file.md @@ -355,6 +355,18 @@ Configuration items related to performance. - Default: `NO_PRIORITY` - Optional values: `NO_PRIORITY`, `LOW_PRIORITY`, `HIGH_PRIORITY` and `DELAYED`. +### `distinct-agg-push-down` + +- Determines whether the optimizer executes the operation that pushes down the aggregation function with `Distinct` (such as `select count(distinct a) from t`) to Coprocessors. +- Default: `false` +- This variable is the initial value of the system variable [`tidb_opt_distinct_agg_push_down`](/system-variables.md#tidb_opt_distinct_agg_push_down). + +### `nested-loop-join-cache-capacity` + ++ The maximum memory usage for the Least Recently Used (LRU) algorithm of the nested loop join cache (in bytes). ++ Default value: `20971520` ++ When `nested-loop-join-cache-capacity` is set to `0`, nested loop join cache is disabled by default. When the LRU size is larger than the value of `nested-loop-join-cache-capacity`, the elements in the LRU are removed. + ## prepared-plan-cache The Plan Cache configuration of the `PREPARE` statement.