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|
+----+------+---+
+----+------+---+

Related Statements

• DROP TABLE
• ALTER TABLE