The ALTER DATABASE .. DROP REGION
statement drops a region from a multi-region database. While CockroachDB processes an index modification or changing a table to or from a REGIONAL BY ROW
table, attempting to drop a region from the database containing that REGIONAL BY ROW
table will produce an error. Similarly, while this statement is running, all index modifications and locality changes on REGIONAL BY ROW
tables will be blocked.
This is an enterprise-only feature. Request a 30-day trial license to try it out.
DROP REGION
is a subcommand of ALTER DATABASE
.
Synopsis
Parameters
Parameter | Description |
---|---|
database_name |
The database from which you are dropping a region. |
region_name |
The region being dropped from this database. Allowed values include any region present in SHOW REGIONS FROM DATABASE database_name .You can only drop the primary region from a multi-region database if it's the last remaining region. |
Required privileges
To drop a region from a database, the user must have one of the following:
- Membership to the
admin
role for the cluster. - Membership to the owner role, or the
CREATE
privilege, for the database and allREGIONAL BY ROW
tables in the database.
Examples
Setup
Only a cluster region specified at node startup can be used as a database region.
To follow along with the examples below, start a demo cluster with the --global
flag to simulate a multi-region cluster:
$ cockroach demo --global --nodes 9 --no-example-database
To see the regions available to the databases in the cluster, use a SHOW REGIONS FROM CLUSTER
statement:
SHOW REGIONS FROM CLUSTER;
region | zones
---------------+----------
europe-west1 | {b,c,d}
us-east1 | {b,c,d}
us-west1 | {a,b,c}
(3 rows)
Set the primary region
Suppose you have a database foo
in your cluster, and you want to make it a multi-region database.
To add the first region to the database, or to set an already-added region as the primary region, use a SET PRIMARY REGION
statement:
ALTER DATABASE foo SET PRIMARY REGION "us-east1";
ALTER DATABASE PRIMARY REGION
Add regions to a database
To add more regions to a database that already has at least one region, use an ADD REGION
statement:
ALTER database foo ADD region "us-west1";
ALTER DATABASE ADD REGION
ALTER database foo ADD region "europe-west1";
ALTER DATABASE ADD REGION
View a database's regions
To view the regions associated with a multi-region database, use a SHOW REGIONS FROM DATABASE
statement:
SHOW REGIONS FROM DATABASE foo;
database | region | primary | zones
-----------+--------------+---------+----------
foo | us-east1 | true | {b,c,d}
foo | europe-west1 | false | {b,c,d}
foo | us-west1 | false | {a,b,c}
(3 rows)
Drop regions from a database
To drop a region from a multi-region database, use a DROP REGION
statement:
ALTER DATABASE foo DROP REGION "us-west1";
ALTER DATABASE DROP REGION
SHOW REGIONS FROM DATABASE foo;
database | region | primary | zones
-----------+--------------+---------+----------
foo | us-east1 | true | {b,c,d}
foo | europe-west1 | false | {b,c,d}
(2 rows)
You can only drop the primary region from a multi-region database if it's the last remaining region.
If you try to drop the primary region when there is more than one region, CockroachDB will return an error:
ALTER DATABASE foo DROP REGION "us-east1";
ERROR: cannot drop region "us-east1"
SQLSTATE: 42P12
HINT: You must designate another region as the primary region using ALTER DATABASE foo PRIMARY REGION <region name> or remove all other regions before attempting to drop region "us-east1"
ALTER DATABASE foo DROP REGION "europe-west1";
ALTER DATABASE DROP REGION
SHOW REGIONS FROM DATABASE foo;
database | region | primary | zones
-----------+----------+---------+----------
foo | us-east1 | true | {b,c,d}
(1 row)
ALTER DATABASE foo DROP REGION "us-east1";
ALTER DATABASE DROP REGION
SHOW REGIONS FROM DATABASE foo;
database | region | primary | zones
-----------+--------+---------+--------
(0 rows)
You cannot drop a region from a database if the databases uses REGION
survival goal and there are only three regions configured on the database:
ALTER DATABASE foo SET PRIMARY REGION "us-east1";
ALTER DATABASE PRIMARY REGION
ALTER DATABASE foo ADD REGION "us-west1";
ALTER DATABASE ADD REGION
ALTER DATABASE foo ADD REGION "europe-west1";
ALTER DATABASE ADD REGION
ALTER DATABASE foo DROP REGION "us-west1";
ERROR: at least 3 regions are required for surviving a region failure
SQLSTATE: 22023
HINT: you must add additional regions to the database or change the survivability goal