# ALTER SEQUENCE

The `ALTER SEQUENCE` statement changes the name, increment values, and other settings of a sequence.

Note:

This statement performs a schema change. For more information about how online schema changes work in CockroachDB, see Online Schema Changes.

## Required privileges

The user must have the `CREATE` privilege on the parent database.

## Synopsis

## Parameters

Parameter | Description
--- | ---
`IF EXISTS` | Modify the sequence only if it exists; if it does not exist, do not return an error.
`sequence_name` | The name of the sequence you want to modify.
`INCREMENT` | The new value by which the sequence is incremented. A negative number creates a descending sequence. A positive number creates an ascending sequence.
`MINVALUE` | The new minimum value of the sequence. Default: `1`
`MAXVALUE` | The new maximum value of the sequence. Default: `9223372036854775807`
`START` | The value the sequence starts at if you `RESTART` or if the sequence hits the `MAXVALUE` and `CYCLE` is set. `RESTART` and `CYCLE` are not implemented yet.
`CYCLE` | The sequence will wrap around when the sequence value hits the maximum or minimum value. If `NO CYCLE` is set, the sequence will not wrap.

## Examples

### Change the increment value of a sequence

In this example, we're going to change the increment value of a sequence from its current state (i.e., `1`) to `2`.

    > ALTER SEQUENCE customer_seq INCREMENT 2;

Next, we'll add another record to the table and check that the new record adheres to the new sequence.

    > INSERT INTO customer_list (customer, address) VALUES ('Marie', '333 Ocean Ave');

    > SELECT * FROM customer_list;

    +----+----------+--------------------+
    | id | customer |      address       |
    +----+----------+--------------------+
    |  1 | Lauren   | 123 Main Street    |
    |  2 | Jesse    | 456 Broad Ave      |
    |  3 | Amruta   | 9876 Green Parkway |
    |  5 | Marie    | 333 Ocean Ave      |
    +----+----------+--------------------+

### Set the next value of a sequence

In this example, we're going to change the next value of the example sequence (`customer_seq`). Currently, the next value will be `7` (i.e., `5` + `INCREMENT 2`). We will change the next value to `20`.

Note:
You cannot set a value outside the `MAXVALUE` or `MINVALUE` of the sequence.

    > SELECT setval('customer_seq', 20, false);

    +--------+
    | setval |
    +--------+
    |     20 |
    +--------+

Note:

The `setval('seq_name', value, is_called)` function in CockroachDB SQL mimics the `setval()` function in PostgreSQL, but it does not store the `is_called` flag. Instead, it sets the value to `val - increment` for `false` or `val` for `true`.

Let's add another record to the table to check that the new record adheres to the new next value.

    > INSERT INTO customer_list (customer, address) VALUES ('Lola', '333 Schermerhorn');

    +----+----------+--------------------+
    | id | customer |      address       |
    +----+----------+--------------------+
    |  1 | Lauren   | 123 Main Street    |
    |  2 | Jesse    | 456 Broad Ave      |
    |  3 | Amruta   | 9876 Green Parkway |
    |  5 | Marie    | 333 Ocean Ave      |
    | 20 | Lola     | 333 Schermerhorn   |
    +----+----------+--------------------+

## See also

- `RENAME SEQUENCE`
- `CREATE SEQUENCE`
- `DROP SEQUENCE`
- Functions and Operators
- Other SQL Statements
- Online Schema Changes