Truncate Table

Truncate allows the data in a table or database to be removed, while preserving their existence. This is a lightweight operation which cannot be reversed.

TRUNCATE Statements

TRUNCATE TABLE

TRUNCATE TABLE [IF EXISTS] [db.]name [ON CLUSTER cluster]

Removes all data from a table. When the clause IF EXISTS is omitted, the query returns an error if the table does not exist.

The TRUNCATE query is not supported for View, File, URL, Buffer and Null table engines.

You can use the alter_sync setting to set up waiting for actions to be executed on replicas.

You can specify how long (in seconds) to wait for inactive replicas to execute TRUNCATE queries with the replication_wait_for_inactive_replica_timeout setting.

Note

If the alter_sync is set to 2 and some replicas are not active for more than the time, specified by the replication_wait_for_inactive_replica_timeout setting, then an exception UNFINISHED is thrown.

TRUNCATE ALL TABLES

TRUNCATE ALL TABLES FROM [IF EXISTS] db [ON CLUSTER cluster]

Removes all data from all tables in a database.

TRUNCATE DATABASE

TRUNCATE DATABASE [IF EXISTS] db [ON CLUSTER cluster]

Removes all tables from a database but keeps the database itself. When the clause IF EXISTS is omitted, the query returns an error if the database does not exist.