Alter a table

You can use the ALTER TABLE statement to change the default value, encoding, compression, or block size of existing columns in a Kudu table, or to change Impala's metadata relating to a given Kudu table by altering the table's properties.

The Impala SQL Reference ALTER TABLE includes a Kudu Considerations section with examples and a list of constraints relevant to altering a Kudu table in Impala.

Altering the table properties

important

Alter table statements do not make any change to the Kudu data for EXTERNAL tables.

Rename an external Impala table

ALTER TABLE my_table RENAME TO my_new_table;

If you rename an external table, it does not change the name of the Kudu table.

If you rename a managed table, the name of the Kudu table is changed accordingly.

Remapping an external table to a different Kudu table

If another application has renamed a Kudu table under Impala, it is possible to re-map an external table to point to a different Kudu table name.

ALTER TABLE my_external_table_
SET TBLPROPERTIES('kudu.table_name' = 'some_other_kudu_table')

Change the Kudu master addresses

ALTER TABLE my_table SET TBLPROPERTIES('kudu.master_addresses' = 'kudu-original-master.example.com:7051,kudu-new-master.example.com:7051');

Change an internally-managed table to external

ALTER TABLE my_table SET TBLPROPERTIES('EXTERNAL' = 'TRUE');