*: remove most of Telemetry related contents (#18759)

Author: bb7133

Diff for: TOC.md

@@ -739,7 +739,6 @@
       - [`ADMIN RESUME DDL`](/sql-statements/sql-statement-admin-resume-ddl.md)
       - [`ADMIN [SET|SHOW|UNSET] BDR ROLE`](/sql-statements/sql-statement-admin-bdr-role.md)
       - [`ADMIN SHOW DDL [JOBS|JOB QUERIES]`](/sql-statements/sql-statement-admin-show-ddl.md)
-      - [`ADMIN SHOW TELEMETRY`](/sql-statements/sql-statement-admin-show-telemetry.md)
       - [`ALTER DATABASE`](/sql-statements/sql-statement-alter-database.md)
       - [`ALTER INSTANCE`](/sql-statements/sql-statement-alter-instance.md)
       - [`ALTER PLACEMENT POLICY`](/sql-statements/sql-statement-alter-placement-policy.md)

Diff for: keywords.md

@@ -687,8 +687,6 @@ The following list shows the keywords in TiDB. Reserved keywords are marked with
 - TABLESAMPLE (R)
 - TABLESPACE
 - TABLE_CHECKSUM
-- TELEMETRY
-- TELEMETRY_ID
 - TEMPORARY
 - TEMPTABLE
 - TERMINATED (R)

Diff for: pd-configuration-file.md

@@ -485,9 +485,12 @@ Configuration items related to the [TiDB Dashboard](/dashboard/dashboard-intro.m
 
 ### `enable-telemetry`
 
-+ Determines whether to enable the telemetry collection feature in TiDB Dashboard.
+> **Warning:**
+>
+> Starting from v8.1.0, the telemetry feature in TiDB Dashboard is removed, and this configuration item is no longer functional. It is retained solely for compatibility with earlier versions.
+
++ Before v8.1.0, this configuration item controls whether to enable telemetry collection in TiDB Dashboard.
 + Default value: `false`
-+ See [Telemetry](/telemetry.md) for details.
 
 ## `replication-mode`
 

Diff for: releases/release-6.1.5.md

@@ -15,8 +15,8 @@ Quick access: [Quick start](https://docs.pingcap.com/tidb/v6.1/quick-start-with-
 
 - Starting from February 20, 2023, the [telemetry feature](/telemetry.md) is disabled by default in new versions of TiDB and TiDB Dashboard, including v6.1.5, and usage information is not collected and shared with PingCAP. Before upgrading to these versions, if the cluster uses the default telemetry configuration, the telemetry feature is disabled after the upgrade. See [TiDB Release Timeline](/releases/release-timeline.md) for a specific version.
 
-    - The default value of the [`tidb_enable_telemetry`](/system-variables.md#tidb_enable_telemetry-new-in-v402) system variable is changed from `ON` to `OFF`.
-    - The default value of the TiDB [`enable-telemetry`](/tidb-configuration-file.md#enable-telemetry-new-in-v402) configuration item is changed from `true` to `false`.
+    - The default value of the [`tidb_enable_telemetry`](/system-variables.md#tidb_enable_telemetry-new-in-v402-and-deprecated-in-v810) system variable is changed from `ON` to `OFF`.
+    - The default value of the TiDB [`enable-telemetry`](/tidb-configuration-file.md#enable-telemetry-new-in-v402-and-deprecated-in-v810) configuration item is changed from `true` to `false`.
     - The default value of the PD [`enable-telemetry`](/pd-configuration-file.md#enable-telemetry) configuration item is changed from `true` to `false`.
 
 - Starting from v1.11.3, the telemetry feature is disabled by default in newly deployed TiUP, and usage information is not collected. If you upgrade from a TiUP version earlier than v1.11.3 to v1.11.3 or a later version, the telemetry feature keeps the same status as before the upgrade.

Diff for: releases/release-6.5.1.md

@@ -15,8 +15,8 @@ Quick access: [Quick start](https://docs.pingcap.com/tidb/v6.5/quick-start-with-
 
 - Starting from February 20, 2023, the [telemetry feature](/telemetry.md) is disabled by default in new versions of TiDB and TiDB Dashboard, including v6.5.1, and usage information is not collected and shared with PingCAP. Before upgrading to these versions, if the cluster uses the default telemetry configuration, the telemetry feature is disabled after the upgrade. See [TiDB Release Timeline](/releases/release-timeline.md) for specific versions.
 
-    - The default value of the [`tidb_enable_telemetry`](/system-variables.md#tidb_enable_telemetry-new-in-v402) system variable is changed from `ON` to `OFF`.
-    - The default value of the TiDB [`enable-telemetry`](/tidb-configuration-file.md#enable-telemetry-new-in-v402) configuration item is changed from `true` to `false`.
+    - The default value of the [`tidb_enable_telemetry`](/system-variables.md#tidb_enable_telemetry-new-in-v402-and-deprecated-in-v810) system variable is changed from `ON` to `OFF`.
+    - The default value of the TiDB [`enable-telemetry`](/tidb-configuration-file.md#enable-telemetry-new-in-v402-and-deprecated-in-v810) configuration item is changed from `true` to `false`.
     - The default value of the PD [`enable-telemetry`](/pd-configuration-file.md#enable-telemetry) configuration item is changed from `true` to `false`.
 
 - Starting from v1.11.3, the telemetry feature is disabled by default in newly deployed TiUP, and usage information is not collected. If you upgrade from a TiUP version earlier than v1.11.3 to v1.11.3 or a later version, the telemetry feature keeps the same status as before the upgrade.

Diff for: releases/release-6.6.0.md

@@ -356,7 +356,7 @@ In v6.6.0-DMR, the key new features and improvements are as follows:
 | [`tidb_enable_foreign_key`](/system-variables.md#tidb_enable_foreign_key-new-in-v630) | Modified | This variable controls whether to enable the foreign key feature. The default value changes from `OFF` to `ON`, which means enabling foreign key by default. |
 | `tidb_enable_general_plan_cache` | Modified | This variable controls whether to enable General Plan Cache. Starting from v6.6.0, this variable is renamed to [`tidb_enable_non_prepared_plan_cache`](/system-variables.md#tidb_enable_non_prepared_plan_cache). |
 | [`tidb_enable_historical_stats`](/system-variables.md#tidb_enable_historical_stats) | Modified | This variable controls whether to enable historical statistics. The default value changes from `OFF` to `ON`, which means that historical statistics are enabled by default. |
-| [`tidb_enable_telemetry`](/system-variables.md#tidb_enable_telemetry-new-in-v402) | Modified | The default value changes from `ON` to `OFF`, which means that telemetry is disabled by default in TiDB. |
+| [`tidb_enable_telemetry`](/system-variables.md#tidb_enable_telemetry-new-in-v402-and-deprecated-in-v810) | Modified | The default value changes from `ON` to `OFF`, which means that telemetry is disabled by default in TiDB. |
 | `tidb_general_plan_cache_size` | Modified | This variable controls the maximum number of execution plans that can be cached by General Plan Cache. Starting from v6.6.0, this variable is renamed to [`tidb_non_prepared_plan_cache_size`](/system-variables.md#tidb_non_prepared_plan_cache_size). |
 | [`tidb_replica_read`](/system-variables.md#tidb_replica_read-new-in-v40) | Modified | A new value option `learner` is added for this variable to specify the learner replicas with which TiDB reads data from read-only nodes. |
 | [`tidb_replica_read`](/system-variables.md#tidb_replica_read-new-in-v40) | Modified | A new value option `prefer-leader` is added for this variable to improve the overall read availability of TiDB clusters. When this option is set, TiDB prefers to read from the leader replica. When the performance of the leader replica significantly decreases, TiDB automatically reads from follower replicas. |
@@ -385,7 +385,7 @@ In v6.6.0-DMR, the key new features and improvements are as follows:
 | TiKV  | `raftdb.enable-statistics` | Deleted | This configuration item specifies whether to enable Raft RocksDB statistics. Starting from v6.6.0, this item is deleted. Raft RocksDB statistics are enabled for all clusters by default to help diagnostics. For details, see [#13942](https://github.com/tikv/tikv/pull/13942). |
 | TiKV | `storage.block-cache.shared` | Deleted | Starting from v6.6.0, this configuration item is deleted, and the block cache is enabled by default and cannot be disabled. For details, see [#12936](https://github.com/tikv/tikv/issues/12936). |
 | DM | `on-duplicate` |  Deleted | This configuration item controls the methods to resolve conflicts during the full import phase. In v6.6.0, new configuration items `on-duplicate-logical` and `on-duplicate-physical` are introduced to replace `on-duplicate`. |
-| TiDB | [`enable-telemetry`](/tidb-configuration-file.md#enable-telemetry-new-in-v402) | Modified | Starting from v6.6.0, the default value changes from `true` to `false`, which means that telemetry is disabled by default in TiDB. |
+| TiDB | [`enable-telemetry`](/tidb-configuration-file.md#enable-telemetry-new-in-v402-and-deprecated-in-v810) | Modified | Starting from v6.6.0, the default value changes from `true` to `false`, which means that telemetry is disabled by default in TiDB. |
 | TiKV  | [`rocksdb.defaultcf.block-size`](/tikv-configuration-file.md#block-size) and [`rocksdb.writecf.block-size`](/tikv-configuration-file.md#block-size)  |  Modified  |   The default values change from `64K` to `32K`.  |
 | TiKV | [`rocksdb.defaultcf.block-cache-size`](/tikv-configuration-file.md#block-cache-size), [`rocksdb.writecf.block-cache-size`](/tikv-configuration-file.md#block-cache-size), [`rocksdb.lockcf.block-cache-size`](/tikv-configuration-file.md#block-cache-size) | Deprecated | Starting from v6.6.0, these configuration items are deprecated. For details, see [#12936](https://github.com/tikv/tikv/issues/12936). |
 | PD | [`enable-telemetry`](/pd-configuration-file.md#enable-telemetry) | Modified | Starting from v6.6.0, the default value changes from `true` to `false`, which means that telemetry is disabled by default in TiDB Dashboard. |

Diff for: releases/release-8.1.0.md

@@ -173,6 +173,8 @@ Compared with the previous LTS 7.5.0, 8.1.0 includes new features, improvements,
 
 | Variable name | Change type | Description |
 |--------|------------------------------|------|
+| [`tidb_enable_telemetry`](/system-variables.md#tidb_enable_telemetry-new-in-v402-and-deprecated-in-v810) | Deprecated | Starting from v8.1.0, the telemetry feature in TiDB is removed, and this variable is no longer functional. It is retained solely for compatibility with earlier versions.
+ |
 | [`tidb_auto_analyze_ratio`](/system-variables.md#tidb_auto_analyze_ratio) | Modified | Changes the value range from `[0, 18446744073709551615]` to `(0, 1]`. |
 | [`tidb_enable_dist_task`](/system-variables.md#tidb_enable_dist_task-new-in-v710) | Modified | Changes the default value from `OFF` to `ON`. This means that Distributed eXecution Framework (DXF) is enabled by default, which fully utilizes the resources of the TiDB cluster and greatly improves the performance of `ADD INDEX` and `IMPORT INTO` tasks. If you want to upgrade a cluster with the DXF enabled to v8.1.0 or later, disable the DXF (by setting `tidb_enable_dist_task` to `OFF`) before the upgrade, which avoids `ADD INDEX` operations during the upgrade causing data index inconsistency. After the upgrade, you can manually enable the DXF. |
 | [`tidb_service_scope`](/system-variables.md#tidb_service_scope-new-in-v740) | Modified | Changes the optional value from `""` or `background` to a string with a length of up to 64 characters, which enables you to control the service scope of each TiDB node more flexibly. Valid characters include digits `0-9`, letters `a-zA-Z`, underscores `_`, and hyphens `-`. The Distributed eXecution Framework (DXF) determines which TiDB nodes can be scheduled to execute distributed tasks based on the value of this variable. For specific rules, see [Task scheduling](/tidb-distributed-execution-framework.md#task-scheduling). |
@@ -181,7 +183,9 @@ Compared with the previous LTS 7.5.0, 8.1.0 includes new features, improvements,
 
 | Configuration file | Configuration parameter | Change type | Description |
 | -------- | -------- | -------- | -------- |
+| TiDB| [`enable-telemetry`](/tidb-configuration-file.md#enable-telemetry-new-in-v402-and-deprecated-in-v810) | Deprecated | Starting from v8.1.0, the telemetry feature in TiDB is removed, and this configuration item is no longer functional. It is retained solely for compatibility with earlier versions. |
 | TiDB| [`concurrently-init-stats`](/tidb-configuration-file.md#concurrently-init-stats-new-in-v810-and-v752) | Newly added | Controls whether to initialize statistics concurrently during TiDB startup. The default value is `false`. |
+| PD | [`enable-telemetry`](/pd-configuration-file.md#enable-telemetry) | Deprecated | Starting from v8.1.0, the telemetry feature in TiDB Dashboard is removed, and this configuration item is no longer functional. It is retained solely for compatibility with earlier versions. |
 | TiDB Lightning | [`conflict.max-record-rows`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-configuration) | Modified | Starting from v8.1.0, there is no need to configure `conflict.max-record-rows` manually, because TiDB Lightning automatically assigns the value of `conflict.max-record-rows` with the value of `conflict.threshold`, regardless of the user input. `conflict.max-record-rows` will be deprecated in a future release. |
 | TiDB Lightning | [`conflict.threshold`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) | Modified | Changes the default value from `9223372036854775807` to `10000` to quickly interrupt abnormal tasks so that you can make corresponding adjustments as soon as possible. This saves time and computational resources by avoiding the scenario where a large amount of conflicting data is discovered after the import, caused by abnormal data sources or incorrect table schema definitions. |
 | TiCDC | [`security.client-allowed-user`](/ticdc/ticdc-server-config.md#cdc-server-configuration-file-parameters) | Newly added | Lists the usernames that are allowed for client authentication. Authentication requests with usernames not in this list will be rejected. The default value is null. |
@@ -192,6 +196,12 @@ Compared with the previous LTS 7.5.0, 8.1.0 includes new features, improvements,
 
 ## Deprecated features
 
+* Starting from v8.1.0, the telemetry feature in TiDB and TiDB Dashboard is removed:
+
+    * The system variable [`tidb_enable_telemetry`](/system-variables.md#tidb_enable_telemetry-new-in-v402-and-deprecated-in-v810), the TiDB configuration item [`enable-telemetry`](/tidb-configuration-file.md#enable-telemetry-new-in-v402-and-deprecated-in-v810), and the PD configuration item [`enable-telemetry`](/pd-configuration-file.md#enable-telemetry) are deprecated and no longer functional.
+    * The `ADMIN SHOW TELEMETRY` syntax is removed.
+    * The `TELEMETRY` and `TELEMETRY_ID` keywords are removed.
+
 * It is planned to redesign [the auto-evolution of execution plan bindings](/sql-plan-management.md#baseline-evolution) in subsequent releases, and the related variables and behavior will change.
 * The TiDB Lightning parameter [`conflict.max-record-rows`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) is scheduled for deprecation in a future release and will be subsequently removed. This parameter will be replaced by `conflict.threshold`, which means that the maximum number of conflicting records is consistent with the maximum number of conflicting records that can be tolerated in a single import task.
 * Starting from v8.0.0, TiDB Lightning deprecates the [old version of conflict detection](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#the-old-version-of-conflict-detection-deprecated-in-v800) strategy for the physical import mode, and enables you to control the conflict detection strategy for both logical and physical import modes via the [`conflict.strategy`](/tidb-lightning/tidb-lightning-configuration.md) parameter. The [`duplicate-resolution`](/tidb-lightning/tidb-lightning-configuration.md) parameter for the old version of conflict detection will be removed in a future release.