Purpose

Use the ALTER SEQUENCE statement to change the increment, minimum and maximum values, cached numbers, and behavior of an existing sequence. This statement affects only future sequence numbers.

Prerequisites

The sequence must be in your own schema, or you must have the ALTER object privilege on the sequence, or you must have the ALTER ANY SEQUENCE system privilege.

Syntax

alter_sequence::=

Description of the illustration alter_sequence.eps

Semantics

The keywords and parameters in this statement serve the same purposes they serve when you create a sequence.

• To restart the sequence at a different number, you must drop and re-create it.

• If you change the INCREMENT BY value before the first invocation of NEXTVAL, then some sequence numbers will be skipped. Therefore, if you want to retain the original START WITH value, you must drop the sequence and re-create it with the original START WITH value and the new INCREMENT BY value.

• If you alter the sequence by specifying the KEEP or NOKEEP clause between runtime and failover of a request, then the original value of NEXTVAL is not retained during replay for Application Continuity for that request.

• Oracle Database performs some validations. For example, a new MAXVALUE cannot be imposed that is less than the current sequence number.

  See Also:

  CREATE SEQUENCE for information on creating a sequence and DROP SEQUENCE for information on dropping and re-creating a sequence

Examples

Modifying a Sequence: Examples

This statement sets a new maximum value for the customers_seq sequence, which was created in "Creating a Sequence: Example":

ALTER SEQUENCE customers_seq 
   MAXVALUE 1500;

This statement turns on CYCLE and CACHE for the customers_seq sequence:

ALTER SEQUENCE customers_seq 
   CYCLE
   CACHE 5;