br: update the compatibility information for BR between TiDB versions 6.5.0 and 8.5.0

br/backup-and-restore-overview.md

@@ -130,13 +130,47 @@ Before performing backup and restore, BR compares the TiDB cluster version with
 
 Starting from v7.0.0, TiDB gradually supports performing backup and restore operations through SQL statements. Therefore, it is strongly recommended to use the BR tool of the same major version as the TiDB cluster when backing up and restoring cluster data, and avoid performing data backup and restore operations across major versions. This helps ensure smooth execution of restore operations and data consistency. Starting from v7.6.0, BR restores data in some `mysql` system tables by default, that is, the `--with-sys-table` option is set to `true` by default. When restoring data to a TiDB cluster with a different version, if you encounter an error similar to `[BR:Restore:ErrRestoreIncompatibleSys]incompatible system table` due to different schemas of system tables, you can set `--with-sys-table=false` to skip restoring the system tables and avoid this error.
 
+#### Compatibility matrix for BR versions before TiDB v6.6.0
+
 The compatibility information for BR before TiDB v6.6.0 is as follows:
 
 | Backup version (vertical) \ Restore version (horizontal)   | Restore to TiDB v6.0 | Restore to TiDB v6.1 | Restore to TiDB v6.2 | Restore to TiDB v6.3, v6.4, or v6.5 | Restore to TiDB v6.6 |
 |  ----  |  ----  | ---- | ---- | ---- | ---- |
 | TiDB v6.0, v6.1, v6.2, v6.3, v6.4, or v6.5 snapshot backup | Compatible (known issue [#36379](https://github.com/pingcap/tidb/issues/36379): if backup data contains an empty schema, BR might report an error.) | Compatible | Compatible | Compatible | Compatible (BR must be v6.6) |
 | TiDB v6.3, v6.4, v6.5, or v6.6 log backup| Incompatible | Incompatible | Incompatible | Compatible | Compatible |
 
+#### Compatibility matrix for BR versions between TiDB v6.5 and v8.5 
+
+This section introduces the compatibility information for BR versions between TiDB v6.5 and v8.5, including all long-term support (LTS) versions (v6.5, v7.1, v7.5, v8.1, and v8.5):
+
+> **Note:**
+>
+> Known Issue: In version 7.2.0, some system table fields became case-sensitive, which might cause cross-version backup and restore failures. For more details, see [Issue #43717](https://github.com/pingcap/tidb/issues/43717).
+
+The following table lists the compatibility matrix for full backups:
+
+| Backup version | Compatible restore versions | Incompatible restore versions |
+|:---------|:----------------|:------------------|
+| 6.5.0    | 7.1.0           | 7.5.0 and above   |
+| 7.1.0    | -               | 7.5.0 and above   |
+| 7.5.0    | 7.5.0 and above | -                 |
+| 8.1.0    | 8.1.0 and above | -                 |
+
+The following table lists the compatibility matrix for log backups:
+
+| Backup version | Compatible restore versions | Incompatible restore versions |
+|:---------|:----------------|:------------------|
+| 6.5.0    | 7.1.0           | 7.5.0 and above   |
+| 7.1.0    | -               | 7.5.0 and above   |
+| 7.5.0    | 7.5.0 and above | -                 |
+| 8.1.0    | 8.1.0 and above | -                 |
+
+> **Note:**
+>
+> - When only user data is backed up (full backup or log backup), all versions are compatible with each other.
+> - To maximize the recovery of all system tables (skipping only those with format changes), you can add the following suffix during backup/restore: `--filter '*.*' --filter "__TiDB_BR_Temporary_*.*" --filter '!mysql.*' --filter 'mysql.bind_info' --filter 'mysql.user' --filter 'mysql.global_priv' --filter 'mysql.global_grants' --filter 'mysql.default_roles' --filter 'mysql.role_edges' --filter '!sys.*' --filter '!INFORMATION_SCHEMA.*' --filter '!PERFORMANCE_SCHEMA.*' --filter '!METRICS_SCHEMA.*' --filter '!INSPECTION_SCHEMA.*'`
+> - `-` means that there are no compatibility restrictions for the corresponding scenario.
+
 ## See also
 
 - [TiDB Snapshot Backup and Restore Guide](/br/br-snapshot-guide.md)