PURGE

Permanently removes delete vectors from ROS storage containers so disk space can be reused. PURGE removes all historical data up to and including the Ancient History Mark epoch.

PURGE does not delete temporary tables.

PURGE can temporarily use significant disk space.

Syntax

SELECT PURGE()

Privileges

  • Table owner
  • USAGE privilege on schema

Example

After you delete data from a Vertica table, that data is marked for deletion. To see the data that is marked for deletion, query system table DELETE_VECTORS.

Run PURGE to remove the delete vectors from ROS containers.

=> SELECT * FROM test1;
 number
--------
      3
     12
     33
     87
     43
     99
(6 rows)
=> DELETE FROM test1 WHERE number > 50;
 OUTPUT
--------
      2
(1 row)
=> SELECT * FROM test1;
 number
--------
     43
      3
     12
     33
(4 rows)
=> SELECT node_name, projection_name, deleted_row_count FROM DELETE_VECTORS;
    node_name     | projection_name | deleted_row_count
------------------+-----------------+------------------- 
 v_vmart_node0002 | test1_b1        |                 1
 v_vmart_node0001 | test1_b1        |                 1
 v_vmart_node0001 | test1_b0        |                 1
 v_vmart_node0003 | test1_b0        |                 1
(4 rows)
=> SELECT PURGE();
...
(Table: public.test1) (Projection: public.test1_b0)
(Table: public.test1) (Projection: public.test1_b1)
...
(4 rows)

After the ancient history mark (AHM) advances:

=> SELECT * FROM DELETE_VECTORS;
 (No rows)

See Also