Page History

...

Syntax

TRUNCATE TABLE table_name [PARTITION partition_spec];

partition_spec:
  : (partition_col = partition_col_value, partition_col = partiton_col_value, ...)

...

Removes all rows from a table or partition(s).

...

Currently target table should be native/managed table

...

or exception will be thrown

...

.

Notes

User can specify partial partition spec for truncating multiple partitions at once

...

and omitting partition spec

...

will truncate all partitions in the table

...

.

Alter Table/Partition Statements

Alter table statements enable you to change the structure of an existing table. You can add columns/partitions, change serde, add table and serde properties, or rename the table itself. Similarly, alter table partition statements allow you change the properties of a specific partition in the named table.

...

This command will allow users to change a column's name, data type, comment, or position, or an arbitrary combination of them.

Example:

CREATE TABLE test_change (a int, b int, c int);

...

// will change column a's name to a1

...

ALTER TABLE test_change CHANGE a a1

...

 INT; 

// will change column a's name to a1, a's data type to string, and put it after column b. The new table's structure is: b int, a1 string, c int

...

ALTER TABLE test_change CHANGE

...

 a a1 STRING AFTER b; 

// will change column b's name to b1, and put it as the first column. The new table's structure is: b1 int, a string, c

...

 int
ALTER TABLE test_change CHANGE b b1 INT FIRST; 

NOTE: The column change command will only modify Hive's metadata, and will NOT touch data. Users should make sure the actual data layout conforms with the metadata definition.

...