ALTER SEQUENCE

The ALTER SEQUENCE statement applies a schema change to 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

  • To alter a sequence, the user must have the CREATE privilege on the parent database.
  • To change the schema of a sequence with ALTER SEQUENCE ... SET SCHEMA, or to change the database of a sequence with ALTER SEQUENCE ... RENAME TO, the user must also have the DROP privilege on the sequence.

Syntax

ALTER SEQUENCE IF EXISTS sequence_name RENAME TO sequence_name NO CYCLE MINVALUE MAXVALUE OWNED BY NONE column_name CACHE MINVALUE MAXVALUE INCREMENT BY START WITH integer VIRTUAL SET SCHEMA schema_name OWNER TO role_spec

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.
RENAME TO sequence_name Rename the sequence to sequence_name, which must be unique to its database and follow these identifier rules. Name changes do not propagate to the table(s) using the sequence.

Note that RENAME TO can be used to move a sequence from one database to another, but it cannot be used to move a sequence from one schema to another. To change a sequence's schema, use ALTER SEQUENCE ...SET SCHEMA instead. In a future release, RENAME TO will be limited to changing the name of a sequence, and will not have to the ability to change a sequence's database.
CYCLE/NO 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.
OWNED BY column_name Associates the sequence to a particular column. If that column or its parent table is dropped, the sequence will also be dropped.

Specifying an owner column with OWNED BY replaces any existing owner column on the sequence. To remove existing column ownership on the sequence and make the column free-standing, specify OWNED BY NONE.

Default: NONE
CACHE The number of sequence values to cache in memory for reuse in the session. A cache size of 1 means that there is no cache, and cache sizes of less than 1 are not valid.

Default: 1 (sequences are not cached by default)
MINVALUE The new minimum value of the sequence.

Default: 1
MAXVALUE The new maximum value of the sequence.

Default: 9223372036854775807
INCREMENT The new value by which the sequence is incremented. A negative number creates a descending sequence. A positive number creates an ascending sequence.
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.
VIRTUAL Creates a virtual sequence.

Virtual sequences are sequences that do not generate monotonically increasing values and instead produce values like those generated by the built-in function unique_rowid(). They are intended for use in combination with SERIAL-typed columns.
SET SCHEMA schema_name Change the schema of the sequence to schema_name.
OWNER TO role_spec Change the owner of the sequence to role_spec.

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.

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> CREATE SEQUENCE customer_seq;
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> SHOW CREATE customer_seq;
   table_name  |                                     create_statement
---------------+-------------------------------------------------------------------------------------------
  customer_seq | CREATE SEQUENCE customer_seq MINVALUE 1 MAXVALUE 9223372036854775807 INCREMENT 1 START 1
(1 row)
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> ALTER SEQUENCE customer_seq INCREMENT 2;
   table_name  |                                        create_statement
---------------+--------------------------------------------------------------------------------------------------
  customer_seq | CREATE SEQUENCE public.customer_seq MINVALUE 1 MAXVALUE 9223372036854775807 INCREMENT 2 START 1
(1 row)

Rename a sequence

In this example, we will change the name of sequence.

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> CREATE SEQUENCE even_numbers INCREMENT 2 START 2;
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> SHOW SEQUENCES;
  sequence_schema | sequence_name
------------------+----------------
  public          | even_numbers
(1 row)
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> ALTER SEQUENCE even_numbers RENAME TO even_sequence;
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> SHOW SEQUENCES;
  sequence_schema | sequence_name
------------------+----------------
  public          | even_sequence
(1 row)

Change the database of a sequence

In this example, we will move the sequence we renamed in the first example (even_sequence) from defaultdb (i.e., the default database) to a different database.

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> SHOW SEQUENCES FROM defaultdb;
  sequence_schema | sequence_name
------------------+----------------
  public          | even_sequence
(1 row)
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> CREATE DATABASE mydb;
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> ALTER SEQUENCE even_sequence RENAME TO mydb.even_sequence;
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> SHOW SEQUENCES FROM defaultdb;
  sequence_schema | sequence_name
------------------+----------------
(0 rows)
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> SHOW SEQUENCES FROM mydb;
  sequence_schema | sequence_name
------------------+----------------
  public          | even_sequence
(1 row)

Change the schema of a sequence

Suppose you create a sequence that you would like to add to a new schema called cockroach_labs:

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> CREATE SEQUENCE even_numbers INCREMENT 2 START 2;
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> SHOW SEQUENCES;
  sequence_schema | sequence_name
------------------+----------------
  public          | even_numbers
(1 row)

By default, unqualified sequences created in the database belong to the public schema:

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> SHOW CREATE public.even_numbers;
      table_name      |                                        create_statement
----------------------+--------------------------------------------------------------------------------------------------
  public.even_numbers | CREATE SEQUENCE public.even_numbers MINVALUE 1 MAXVALUE 9223372036854775807 INCREMENT 2 START 2
(1 row)

If the new schema does not already exist, create it:

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> CREATE SCHEMA IF NOT EXISTS cockroach_labs;

Then, change the sequence's schema:

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> ALTER SEQUENCE even_numbers SET SCHEMA cockroach_labs;
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> SHOW CREATE public.even_numbers;
ERROR: relation "public.even_numbers" does not exist
SQLSTATE: 42P01
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> SHOW SEQUENCES;
  sequence_schema | sequence_name
------------------+----------------
  cockroach_labs  | even_numbers
(1 row)
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> SHOW CREATE cockroach_labs.even_numbers;
          table_name          |                                            create_statement
------------------------------+----------------------------------------------------------------------------------------------------------
  cockroach_labs.even_numbers | CREATE SEQUENCE cockroach_labs.even_numbers MINVALUE 1 MAXVALUE 9223372036854775807 INCREMENT 2 START 2
(1 row)

See also

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