FLASHBACK DATABASE

TiDB v6.4.0 introduces the FLASHBACK DATABASE syntax. You can use FLASHBACK DATABASE to restore a database and its data that are deleted by the DROP statement within the Garbage Collection (GC) life time.

You can set the retention time of historical data by configuring the tidb_gc_life_time system variable. The default value is 10m0s. You can query the current safePoint, that is, the time point GC has been performed up to, using the following SQL statement:

  1. SELECT * FROM mysql.tidb WHERE variable_name = 'tikv_gc_safe_point';

As long as a database is deleted by DROP after the tikv_gc_safe_point time, you can use FLASHBACK DATABASE to restore the database.

Syntax

  1. FLASHBACK DATABASE DBName [TO newDBName]

Synopsis

FlashbackDatabaseStmt

FLASHBACK DATABASE - 图1

FlashbackToNewName

FLASHBACK DATABASE - 图2

  1. FlashbackDatabaseStmt ::=
  2.     'FLASHBACK' DatabaseSym DBName FlashbackToNewName
  3. FlashbackToNewName ::=
  4.     ( 'TO' Identifier )?

Notes

  • If the database is deleted before the tikv_gc_safe_point time, you cannot restore the data using the FLASHBACK DATABASE statement. The FLASHBACK DATABASE statement returns an error similar to ERROR 1105 (HY000): Can't find dropped database 'test' in GC safe point 2022-11-06 16:10:10 +0800 CST.

  • You cannot restore the same database multiple times using the FLASHBACK DATABASE statement. Because the database restored by FLASHBACK DATABASE has the same schema ID as the original database, restoring the same database multiple times leads to duplicate schema IDs. In TiDB, the database schema ID must be globally unique.

  • When TiDB Binlog is enabled, note the following when you use FLASHBACK DATABASE:

    • The downstream secondary database must support FLASHBACK DATABASE.
    • The GC life time of the secondary database must be longer than that of the primary database. Otherwise, the latency between the upstream and the downstream might lead to data restoration failure in the downstream.
    • If TiDB Binlog replication encounters an error, you need to filter out the database in TiDB Binlog and then manually import full data for this database.

Example

  • Restore the test database that is deleted by DROP:

    1. DROP DATABASE test;
    1. FLASHBACK DATABASE test;

  • Restore the test database that is deleted by DROP and rename it to test1:

    1. DROP DATABASE test;
    1. FLASHBACK DATABASE test TO test1;

MySQL compatibility

This statement is a TiDB extension to MySQL syntax.