diff --git a/system-variables.md b/system-variables.md index 3e84c5bff2236..d4a36fb372b69 100644 --- a/system-variables.md +++ b/system-variables.md @@ -651,7 +651,7 @@ This variable is an alias for [`last_insert_id`](#last_insert_id). > **Note:** > -> This variable is read-only for [{{{ .starter }}}](https://docs.pingcap.com/tidbcloud/select-cluster-tier#starter) and [{{{ .essential }}}](https://docs.pingcap.com/tidbcloud/select-cluster-tier#essential). +> This variable is read-only for [{{{ .starter }}}](https://docs.pingcap.com/tidbcloud/select-cluster-tier#starter) and [{{{ .essential }}}](https://docs.pingcap.com/tidbcloud/select-cluster-tier#essential). Its effective value is controlled by TiDB Cloud. - Scope: SESSION | GLOBAL - Persists to cluster: Yes @@ -661,6 +661,7 @@ This variable is an alias for [`last_insert_id`](#last_insert_id). - The value should be an integer multiple of 1024. If the value is not divisible by 1024, a warning will be prompted and the value will be rounded down. For example, when the value is set to 1025, the actual value in TiDB is 1024. - The maximum packet size allowed by the server and the client in one transmission of packets. - In the `SESSION` scope, this variable is read-only. +- In Starter deployment mode, the effective value is configured by [`max-allowed-packet`](/tidb-configuration-file.md#max-allowed-packet-new-in-v900). TiDB uses the configured value when initializing sessions and when reporting the global `max_allowed_packet` value. - This variable is compatible with MySQL. ### max_user_connections New in v9.0.0 @@ -889,6 +890,8 @@ mysql> SHOW GLOBAL VARIABLES LIKE 'max_prepared_stmt_count'; > **Note:** > > Currently, this variable is not supported on [TiDB Cloud Dedicated](https://docs.pingcap.com/tidbcloud/select-cluster-tier#tidb-cloud-dedicated). DO **NOT** enable this variable for TiDB Cloud Dedicated clusters. Otherwise, you might get SQL client connection failures. This restriction is a temporary control measure and will be resolved in a future release. +> +> For [{{{ .starter }}}](https://docs.pingcap.com/tidbcloud/select-cluster-tier#starter) and [{{{ .essential }}}](https://docs.pingcap.com/tidbcloud/select-cluster-tier#essential), this variable is read-only and always returns `ON`. - Scope: GLOBAL - Persists to cluster: Yes @@ -904,11 +907,11 @@ mysql> SHOW GLOBAL VARIABLES LIKE 'max_prepared_stmt_count'; -- This variable ensures that all connections to TiDB are either on a local socket, or using TLS. +- For TiDB Cloud, secure connection behavior is managed by the service. For [{{{ .starter }}}](https://docs.pingcap.com/tidbcloud/select-cluster-tier#starter) and [{{{ .essential }}}](https://docs.pingcap.com/tidbcloud/select-cluster-tier#essential), this variable is exposed as `ON` and cannot be changed by SQL statements. -- Setting this variable to `ON` requires you to connect to TiDB from a session that has TLS enabled. This helps prevent lock-out scenarios when TLS is not configured correctly. +- For TiDB Self-Managed, setting this variable to `ON` requires you to connect to TiDB from a session that has TLS enabled. This helps prevent lock-out scenarios when TLS is not configured correctly. - This setting was previously a `tidb.toml` option (`security.require-secure-transport`), but changed to a system variable starting from TiDB v6.1.0. - Starting from v6.5.6, v7.1.2, v7.5.1, and v8.0.0, when Security Enhanced Mode (SEM) is enabled, setting this variable to `ON` is prohibited to avoid potential connectivity issues for users. diff --git a/tidb-cloud/limited-sql-features.md b/tidb-cloud/limited-sql-features.md index efa8101580cb6..d3fec85a2f6ec 100644 --- a/tidb-cloud/limited-sql-features.md +++ b/tidb-cloud/limited-sql-features.md @@ -125,10 +125,10 @@ TiDB Cloud works with almost all workloads that TiDB supports, but there are som |:-|:-|:-| | `datadir` | No limitation | Not supported [^1] | | `interactive_timeout` | No limitation | Read-only [^10] | -| `max_allowed_packet` | No limitation | Read-only [^10] | +| `max_allowed_packet` | No limitation | Read-only; controlled by TiDB Cloud [^10] | | `plugin_dir` | No limitation | Not supported [^8] | | `plugin_load` | No limitation | Not supported [^8] | -| `require_secure_transport` | Not supported [^12] | Read-only [^10] | +| `require_secure_transport` | Not supported [^12] | Read-only and always `ON` [^10] | | `skip_name_resolve` | No limitation | Read-only [^10] | | `sql_log_bin` | No limitation | Read-only [^10] | | `tidb_analyze_skip_column_types` | No limitation | Read-only [^10] | diff --git a/tidb-configuration-file.md b/tidb-configuration-file.md index d28d953d16f40..7548c27d0406b 100644 --- a/tidb-configuration-file.md +++ b/tidb-configuration-file.md @@ -43,6 +43,15 @@ The TiDB configuration file supports more options than command-line parameters. + Minimum value: `1` + Maximum value: `1048576` +### `max-allowed-packet` New in v9.0.0 + ++ Configures the effective value of [`max_allowed_packet`](/system-variables.md#max_allowed_packet-new-in-v610) in Starter deployment mode. ++ Default value: `67108864` (64 MiB) ++ Minimum value: `1024` ++ Maximum value: `1073741824` ++ The value must be an integer multiple of `1024`. ++ This configuration item takes effect only in Starter deployment mode. In other deployment modes, configure the packet size by using the `max_allowed_packet` system variable. + ### `temp-dir` New in v6.3.0 + File system location used by TiDB to store temporary data. If a feature requires local storage in TiDB nodes, TiDB stores the corresponding temporary data in this location. @@ -521,7 +530,7 @@ Configuration items related to performance. - The size limit of a single key-value record in a transaction. If the size limit is exceeded, TiDB returns the `entry too large` error. The maximum value of this configuration item does not exceed `125829120` (120 MB). - Starting from v7.6.0, you can use the system variable [`tidb_txn_entry_size_limit`](/system-variables.md#tidb_txn_entry_size_limit-new-in-v760) to dynamically modify the value of this configuration item. - Note that TiKV has a similar limit. If the data size of a single write request exceeds [`raft-entry-max-size`](/tikv-configuration-file.md#raft-entry-max-size), which is 8 MB by default, TiKV refuses to process this request. When a table has a row of large size, you need to modify both configurations at the same time. -- The default value of [`max_allowed_packet`](/system-variables.md#max_allowed_packet-new-in-v610) (the maximum size of a packet for the MySQL protocol) is 67108864 (64 MiB). If a row is larger than `max_allowed_packet`, the row gets truncated. +- The default value of [`max_allowed_packet`](/system-variables.md#max_allowed_packet-new-in-v610) (the maximum size of a packet for the MySQL protocol) is 67108864 (64 MiB). In Starter deployment mode, its effective value is configured by [`max-allowed-packet`](#max-allowed-packet-new-in-v900). If a row is larger than `max_allowed_packet`, the row gets truncated. - The default value of [`txn-total-size-limit`](#txn-total-size-limit) (the size limit of a single transaction in TiDB) is 100 MiB. If you increase the `txn-entry-size-limit` value to be over 100 MiB, you need to increase the `txn-total-size-limit` value accordingly. ### `txn-total-size-limit`