diff --git a/develop/dev-guide-connection-parameters.md b/develop/dev-guide-connection-parameters.md index 21b1962664fdf..afe34d7f12784 100644 --- a/develop/dev-guide-connection-parameters.md +++ b/develop/dev-guide-connection-parameters.md @@ -272,7 +272,7 @@ INSERT INTO `t` (`a`) VALUES (11) ON DUPLICATE KEY UPDATE `a` = 11; INSERT INTO `t` (`a`) VALUES (12) ON DUPLICATE KEY UPDATE `a` = 12; ``` -The above `INSERT` statements cannot be rewritten into one statement. But if you change the three statements into the following ones: +The above `INSERT` statements cannot be rewritten into one statement. But if you change the three statements as follows, they meet the rewrite requirement: ```sql INSERT INTO `t` (`a`) VALUES (10) ON DUPLICATE KEY UPDATE `a` = VALUES(`a`); @@ -280,7 +280,7 @@ INSERT INTO `t` (`a`) VALUES (11) ON DUPLICATE KEY UPDATE `a` = VALUES(`a`); INSERT INTO `t` (`a`) VALUES (12) ON DUPLICATE KEY UPDATE `a` = VALUES(`a`); ``` -Then they meet the rewrite requirement. The above `INSERT` statements will be rewritten into the following one statement: +The above `INSERT` statements will be rewritten into the following one statement: ```sql INSERT INTO `t` (`a`) VALUES (10), (11), (12) ON DUPLICATE KEY UPDATE a = VALUES(`a`); diff --git a/develop/java-app-best-practices.md b/develop/java-app-best-practices.md index 6b5659afed1f6..bd8bffd96a6c4 100644 --- a/develop/java-app-best-practices.md +++ b/develop/java-app-best-practices.md @@ -166,7 +166,7 @@ insert into t (a) values (11) on duplicate key update a = 11; insert into t (a) values (12) on duplicate key update a = 12; ``` -The above `INSERT` statements cannot be rewritten into one statement. But if you change the three statements into the following ones: +The above `INSERT` statements cannot be rewritten into one statement. But if you change the three statements as follows, they meet the rewrite requirement: ```sql insert into t (a) values (10) on duplicate key update a = values(a); @@ -174,7 +174,7 @@ insert into t (a) values (11) on duplicate key update a = values(a); insert into t (a) values (12) on duplicate key update a = values(a); ``` -Then they meet the rewrite requirement. The above `INSERT` statements will be rewritten into the following one statement: +The above `INSERT` statements will be rewritten into the following one statement: ```sql insert into t (a) values (10), (11), (12) on duplicate key update a = values(a); diff --git a/system-variables.md b/system-variables.md index 9955004ead6a0..2410793f265c5 100644 --- a/system-variables.md +++ b/system-variables.md @@ -2767,7 +2767,7 @@ Assume that you have a cluster with 4 TiDB nodes and multiple TiKV nodes. In thi - Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No - Default value: `ON` - Type: Boolean -- This variable is a switch for [the resource control feature](/tidb-resource-control-ru-groups.md). When this variable is set to `ON`, the TiDB cluster can isolate application resources based on resource groups. +- This variable controls whether to enable [the resource control feature](/tidb-resource-control-ru-groups.md). When this variable is set to `ON`, the TiDB cluster can isolate application resources based on resource groups. ### tidb_enable_reuse_chunk New in v6.4.0 @@ -4592,7 +4592,7 @@ mysql> desc select count(distinct a) from test.t; - Default value: `0` - Range: `[0, 2147483647]` - This variable is used to control the selection of the TiDB Join Reorder algorithm. When the number of nodes participating in Join Reorder is greater than this threshold, TiDB selects the greedy algorithm, and when it is less than this threshold, TiDB selects the dynamic programming algorithm. -- Currently, for OLTP queries, it is recommended to keep the default value. For OLAP queries, it is recommended to set the variable value to 10~15 to get better connection orders in OLAP scenarios. +- Currently, for OLTP queries, it is recommended to keep the default value. For OLAP queries, it is recommended to set the variable value to 10~15 to get better join orders in OLAP scenarios. ### tidb_opt_join_reorder_through_sel New in v8.5.6 diff --git a/tidb-cloud/csv-config-for-import-data.md b/tidb-cloud/csv-config-for-import-data.md index a67ec6c53f013..12cac07fda041 100644 --- a/tidb-cloud/csv-config-for-import-data.md +++ b/tidb-cloud/csv-config-for-import-data.md @@ -67,7 +67,7 @@ The following is the CSV Configuration window when you use the Import Data servi `{"key1": "val1", "key2": "val2"}` - If the content of the CSV source file is saved as JSON in the following way, then consider setting `Backslash escape = True` as follows. But this is not the standard format for CSV. + If a JSON field in the CSV source file is stored in the following way, consider setting `Backslash escape = True`. Note that this is not the standard format for CSV. `"{\"key1\": \"val1\", \"key2\":\"val2\" }"` diff --git a/tidb-scheduling.md b/tidb-scheduling.md index 00a712491dccb..424eccd447730 100644 --- a/tidb-scheduling.md +++ b/tidb-scheduling.md @@ -23,9 +23,9 @@ Now consider about the following situations: * Replicas of all Regions. * If the number of replicas is not enough for some Regions, PD needs to complete them. * If the number of replicas is more than expected (for example, the failed store re-joins into the cluster after recovery), PD needs to delete them. -* Read/Write operations are performed on leaders, which cannot be distributed only on a few individual stores; +* Read/Write operations are performed on leaders, so leaders cannot be concentrated on only a few individual stores; * Not all Regions are hot, so loads of all TiKV stores need to be balanced; -* When Regions are in balancing, data transferring utilizes much network/disk traffic and CPU time, which can influence online services. +* When Regions are being balanced, data transferring utilizes much network/disk traffic and CPU time, which can influence online services. These situations can occur at the same time, which makes it harder to resolve. Also, the whole system is changing dynamically, so a scheduler is needed to collect all information about the cluster, and then adjust the cluster. So, PD is introduced into the TiDB cluster.