The CREATE TABLE ... AS statement creates a new table from a selection query.
Intended use
Tables created with CREATE TABLE ... AS are intended to persist the
result of a query for later reuse.
This can be more efficient than a view when the following two conditions are met:
- The result of the query is used as-is multiple times.
- The copy needs not be kept up-to-date with the original table over time.
When the results of a query are reused multiple times within a larger query, a view is advisable instead. The query optimizer can "peek" into the view and optimize the surrounding query using the primary key and indices of the tables mentioned in the view query.
A view is also advisable when the results must be up-to-date; a view always retrieves the current data from the tables that the view query mentions.
Required privileges
The user must have the CREATE privilege on the parent database.
Synopsis
create_as_col_qual_list ::=
create_as_constraint_def ::=
Parameters
| Parameter | Description |
|---|---|
IF NOT EXISTS |
Create a new table only if a table of the same name does not already exist in the database; if one does exist, do not return an error. Note that IF NOT EXISTS checks the table name only; it does not check if an existing table has the same columns, indexes, constraints, etc., of the new table. |
table_name |
The name of the table to create, which must be unique within its database and follow these identifier rules. When the parent database is not set as the default, the name must be formatted as database.name.The UPSERT and INSERT ON CONFLICT statements use a temporary table called excluded to handle uniqueness conflicts during execution. It's therefore not recommended to use the name excluded for any of your tables. |
column_name |
The name of the column you want to use instead of the name of the column from select_stmt. |
create_as_col_qual_list |
An optional column definition, which may include primary key constraints and column family assignments. |
family_def |
An optional column family definition. Column family names must be unique within the table but can have the same name as columns, constraints, or indexes. |
create_as_constraint_def |
An optional primary key constraint. |
select_stmt |
A selection query to provide the data. |
opt_temp_create_table |
New in v20.1: Defines the table as a session-scoped temporary table. For more information, see Temporary Tables. Support for temporary tables is experimental. The interface and output are subject to change. |
Limitations
Tables created with CREATE TABLE ... AS are not interleaved with other tables.
The default rules for column families apply.
The primary key of tables created with CREATE TABLE ... AS is not automatically derived from the query results. You must specify new primary keys at table creation. For examples, see Specify a primary key and Specify a primary key for partitioning.
Examples
Setup
The following examples use MovR, a fictional vehicle-sharing application, to demonstrate CockroachDB SQL statements. For more information about the MovR example application and dataset, see MovR: A Global Vehicle-sharing App.
To follow along, run cockroach demo to start a temporary, in-memory cluster with the movr dataset preloaded:
$ cockroach demo
Create a table from a SELECT query
> SELECT * FROM users WHERE city = 'new york';
id | city | name | address | credit_card
+--------------------------------------+----------+------------------+-----------------------------+-------------+
00000000-0000-4000-8000-000000000000 | new york | Robert Murphy | 99176 Anderson Mills | 8885705228
051eb851-eb85-4ec0-8000-000000000001 | new york | James Hamilton | 73488 Sydney Ports Suite 57 | 8340905892
0a3d70a3-d70a-4d80-8000-000000000002 | new york | Judy White | 18580 Rosario Ville Apt. 61 | 2597958636
0f5c28f5-c28f-4c00-8000-000000000003 | new york | Devin Jordan | 81127 Angela Ferry Apt. 8 | 5614075234
147ae147-ae14-4b00-8000-000000000004 | new york | Catherine Nelson | 1149 Lee Alley | 0792553487
19999999-9999-4a00-8000-000000000005 | new york | Nicole Mcmahon | 11540 Patton Extensions | 0303726947
(6 rows)
> CREATE TABLE users_ny AS SELECT * FROM users WHERE city = 'new york';
> SELECT * FROM users_ny;
id | city | name | address | credit_card
+--------------------------------------+----------+------------------+-----------------------------+-------------+
00000000-0000-4000-8000-000000000000 | new york | Robert Murphy | 99176 Anderson Mills | 8885705228
051eb851-eb85-4ec0-8000-000000000001 | new york | James Hamilton | 73488 Sydney Ports Suite 57 | 8340905892
0a3d70a3-d70a-4d80-8000-000000000002 | new york | Judy White | 18580 Rosario Ville Apt. 61 | 2597958636
0f5c28f5-c28f-4c00-8000-000000000003 | new york | Devin Jordan | 81127 Angela Ferry Apt. 8 | 5614075234
147ae147-ae14-4b00-8000-000000000004 | new york | Catherine Nelson | 1149 Lee Alley | 0792553487
19999999-9999-4a00-8000-000000000005 | new york | Nicole Mcmahon | 11540 Patton Extensions | 0303726947
(6 rows)
Change column names
This statement creates a copy of an existing table but with changed column names:
> CREATE TABLE users_ny_names (user_id, user_name) AS SELECT id, name FROM users WHERE city = 'new york';
> SELECT * FROM users_ny_names;
user_id | user_name
+--------------------------------------+------------------+
00000000-0000-4000-8000-000000000000 | Robert Murphy
051eb851-eb85-4ec0-8000-000000000001 | James Hamilton
0a3d70a3-d70a-4d80-8000-000000000002 | Judy White
0f5c28f5-c28f-4c00-8000-000000000003 | Devin Jordan
147ae147-ae14-4b00-8000-000000000004 | Catherine Nelson
19999999-9999-4a00-8000-000000000005 | Nicole Mcmahon
(6 rows)
Create a table from a VALUES clause
> CREATE TABLE drivers (id, city, name) AS VALUES (gen_random_uuid(), 'new york', 'Harry Potter'), (gen_random_uuid(), 'seattle', 'Evelyn Martin');
> SELECT * FROM drivers;
id | city | name
+--------------------------------------+----------+---------------+
146eebc4-c913-4678-8ea3-c5797d2b7f83 | new york | Harry Potter
43cafd3b-2537-4fd8-a987-8138f88a22a4 | seattle | Evelyn Martin
(2 rows)
Create a copy of an existing table
> CREATE TABLE users_ny_copy AS TABLE users_ny;
> SELECT * FROM users_ny_copy;
id | city | name | address | credit_card
+--------------------------------------+----------+------------------+-----------------------------+-------------+
00000000-0000-4000-8000-000000000000 | new york | Robert Murphy | 99176 Anderson Mills | 8885705228
051eb851-eb85-4ec0-8000-000000000001 | new york | James Hamilton | 73488 Sydney Ports Suite 57 | 8340905892
0a3d70a3-d70a-4d80-8000-000000000002 | new york | Judy White | 18580 Rosario Ville Apt. 61 | 2597958636
0f5c28f5-c28f-4c00-8000-000000000003 | new york | Devin Jordan | 81127 Angela Ferry Apt. 8 | 5614075234
147ae147-ae14-4b00-8000-000000000004 | new york | Catherine Nelson | 1149 Lee Alley | 0792553487
19999999-9999-4a00-8000-000000000005 | new york | Nicole Mcmahon | 11540 Patton Extensions | 0303726947
(6 rows)
When a table copy is created this way, the copy is not associated to any primary key, secondary index, or constraint that was present on the original table.
Specify a primary key
You can specify the primary key of a new table created from a selection query:
> CREATE TABLE users_ny_pk (id, city, name PRIMARY KEY) AS SELECT id, city, name FROM users WHERE city = 'new york';
> SELECT * FROM users_ny_pk;
id | city | name
+--------------------------------------+----------+------------------+
147ae147-ae14-4b00-8000-000000000004 | new york | Catherine Nelson
0f5c28f5-c28f-4c00-8000-000000000003 | new york | Devin Jordan
051eb851-eb85-4ec0-8000-000000000001 | new york | James Hamilton
0a3d70a3-d70a-4d80-8000-000000000002 | new york | Judy White
19999999-9999-4a00-8000-000000000005 | new york | Nicole Mcmahon
00000000-0000-4000-8000-000000000000 | new york | Robert Murphy
(6 rows)
> SHOW CREATE TABLE users_ny_pk;
table_name | create_statement
+----------------+--------------------------------------------------+
users_ny_extra | CREATE TABLE users_ny_extra (
| id UUID NULL,
| city VARCHAR NULL,
| name VARCHAR NOT NULL,
| CONSTRAINT "primary" PRIMARY KEY (name ASC),
| FAMILY "primary" (id, city, name)
| )
(1 row)
Define column families
You can define the column families of a new table created from a selection query:
> CREATE TABLE users_ny_alt (id PRIMARY KEY FAMILY ids, name, city FAMILY locs, address, credit_card FAMILY payments) AS SELECT id, name, city, address, credit_card FROM users WHERE city = 'new york';
> SELECT * FROM users_ny_alt;
id | name | city | address | credit_card
+--------------------------------------+------------------+----------+-----------------------------+-------------+
00000000-0000-4000-8000-000000000000 | Robert Murphy | new york | 99176 Anderson Mills | 8885705228
051eb851-eb85-4ec0-8000-000000000001 | James Hamilton | new york | 73488 Sydney Ports Suite 57 | 8340905892
0a3d70a3-d70a-4d80-8000-000000000002 | Judy White | new york | 18580 Rosario Ville Apt. 61 | 2597958636
0f5c28f5-c28f-4c00-8000-000000000003 | Devin Jordan | new york | 81127 Angela Ferry Apt. 8 | 5614075234
147ae147-ae14-4b00-8000-000000000004 | Catherine Nelson | new york | 1149 Lee Alley | 0792553487
19999999-9999-4a00-8000-000000000005 | Nicole Mcmahon | new york | 11540 Patton Extensions | 0303726947
(6 rows)
> SHOW CREATE TABLE users_ny_alt;
table_name | create_statement
+--------------+------------------------------------------------+
users_ny_alt | CREATE TABLE users_ny_alt (
| id UUID NOT NULL,
| name VARCHAR NULL,
| city VARCHAR NULL,
| address VARCHAR NULL,
| credit_card VARCHAR NULL,
| CONSTRAINT "primary" PRIMARY KEY (id ASC),
| FAMILY ids (id, name, address),
| FAMILY locs (city),
| FAMILY payments (credit_card)
| )
(1 row)
Specify a primary key for partitioning
If you are partitioning a table based on a primary key, the primary key must be properly defined. To change the primary key after table creation, you can use an ALTER TABLE ... ALTER PRIMARY KEY statement.
Suppose that you want to geo-partition the drivers table that you created with the following statement:
> CREATE TABLE drivers (id, city, name) AS VALUES (gen_random_uuid(), 'new york', 'Harry Potter'), (gen_random_uuid(), 'seattle', 'Evelyn Martin');
> SHOW CREATE TABLE drivers;
table_name | create_statement
+------------+----------------------------------------------+
drivers | CREATE TABLE drivers (
| id UUID NULL,
| city STRING NULL,
| name STRING NULL,
| FAMILY "primary" (id, city, name, rowid)
| )
(1 row)
In order for this table to be properly geo-partitioned with the other tables in the movr dataset, the table must have a composite primary key defined that includes the unique row identifier (id, in this case) and the row locality identifier (city). Use the following statement to change the primary key to a composite primary key:
> CREATE TABLE drivers_pk (id, city, name, PRIMARY KEY (id, city)) AS SELECT id, city, name FROM drivers;
> SHOW CREATE TABLE drivers_pk;
table_name | create_statement
+------------+----------------------------------------------------------+
drivers_pk | CREATE TABLE drivers_pk (
| id UUID NOT NULL,
| city STRING NOT NULL,
| name STRING NULL,
| CONSTRAINT "primary" PRIMARY KEY (id ASC, city ASC),
| FAMILY "primary" (id, city, name)
| )
(1 row)
See also
- Selection Queries
- Simple
SELECTClause CREATE TABLECREATE VIEWINSERTDROP TABLE- Other SQL Statements
ALTER PRIMARY KEYALTER TABLE
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