TRUNCATE TABLE
Description
The TRUNCATE TABLE
statement removes all the rows from a table or partition(s). The table must not be a view
or an external/temporary table. In order to truncate multiple partitions at once, the user can specify the partitions
in partition_spec
. If no partition_spec
is specified it will remove all partitions in the table.
If the table is cached, the command clears cached data of the table and all its dependents that refer to it. The cache will be lazily filled when the next time the table or the dependents are accessed.
Syntax
TRUNCATE TABLE table_identifier [ partition_spec ]
Parameters
-
table_identifier
Specifies a table name, which may be optionally qualified with a database name.
Syntax:
[ database_name. ] table_name
-
partition_spec
An optional parameter that specifies a comma separated list of key and value pairs for partitions.
Syntax:
PARTITION ( partition_col_name = partition_col_val [ , ... ] )
Examples
-- Create table Student with partition
CREATE TABLE Student (name STRING, rollno INT) PARTITIONED BY (age INT);
SELECT * FROM Student;
+----+------+---+
|name|rollno|age|
+----+------+---+
| ABC| 1| 10|
| DEF| 2| 10|
| XYZ| 3| 12|
+----+------+---+
-- Removes all rows from the table in the partition specified
TRUNCATE TABLE Student partition(age=10);
-- After truncate execution, records belonging to partition age=10 are removed
SELECT * FROM Student;
+----+------+---+
|name|rollno|age|
+----+------+---+
| XYZ| 3| 12|
+----+------+---+
-- Removes all rows from the table from all partitions
TRUNCATE TABLE Student;
SELECT * FROM Student;
+----+------+---+
|name|rollno|age|
+----+------+---+
+----+------+---+