CREATE TABLE AS

CREATE TABLE AS — define a new table from the results of a query

Synopsis

CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] table_name
    [ (column_name [, ...] ) ]
    [ USING method ]
    [ WITH ( storage_parameter [= value] [, ... ] ) | WITHOUT OIDS ]
    [ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
    [ TABLESPACE tablespace_name ]
    AS query
    [ WITH [ NO ] DATA ]

CREATE TABLE AS creates a table and fills it with data computed by a SELECT command. The table columns have the names and data types associated with the output columns of the SELECT (except that you can override the column names by giving an explicit list of new column names).

CREATE TABLE AS bears some resemblance to creating a view, but it is really quite different: it creates a new table and evaluates the query just once to fill the new table initially. The new table will not track subsequent changes to the source tables of the query. In contrast, a view re-evaluates its defining SELECT statement whenever it is queried.

CREATE TABLE AS requires CREATE privilege on the schema used for the table.

Parameters

GLOBAL or LOCAL

Ignored for compatibility. Use of these keywords is deprecated; refer to CREATE TABLE for details.

TEMPORARY or TEMP

If specified, the table is created as a temporary table. Refer to CREATE TABLE for details.

UNLOGGED

If specified, the table is created as an unlogged table. Refer to CREATE TABLE for details.

IF NOT EXISTS

Do not throw an error if a relation with the same name already exists; simply issue a notice and leave the table unmodified.

table_name

The name (optionally schema-qualified) of the table to be created.

column_name

The name of a column in the new table. If column names are not provided, they are taken from the output column names of the query.

USING method

This optional clause specifies the table access method to use to store the contents for the new table; the method needs be an access method of type TABLE. See Chapter Table Access Method Interface Definition for more information. If this option is not specified, the default table access method is chosen for the new table. See default_table_access_method for more information.

QHB has the build-in table access method qss. With this option all data of the table and its index(es) and log will be write on disk in encrypted form. See Chapter QSS Secure Storage Module for more information.
QHB also has the build-in access method that implements the storage append_only. It has following properties:

Data modification (updating and deleting) is not allowed.
The quickest possible data inserting is performed.
There is no need for autovacuum.
All index types are supported.
It is possible to use a table partitioning and drop partitions or use TRUNCATE command to delete old data.
The TOAST technique is not supported.
See Chapter Tables APPEND_ONLY for more information.

WITH ( storage_parameter [= value] [, ... ] )

This clause specifies optional storage parameters for the new table; see Storage Parameters in the CREATE TABLE documentation for more information. For backward-compatibility the WITH clause for a table can also include OIDS=FALSE to specify that rows of the new table should contain no OIDs (object identifiers), OIDS=TRUE is not supported anymore.

WITHOUT OIDS

This is backward-compatible syntax for declaring a table WITHOUT OIDS, creating a table WITH OIDS is not supported anymore.

ON COMMIT

The behavior of temporary tables at the end of a transaction block can be controlled using ON COMMIT. The three options are:

PRESERVE ROWS
No special action is taken at the ends of transactions. This is the default behavior.
DELETE ROWS
All rows in the temporary table will be deleted at the end of each transaction block. Essentially, an automatic TRUNCATE is done at each commit.
DROP
The temporary table will be dropped at the end of the current transaction block.

TABLESPACE tablespace_name

The tablespace_name is the name of the tablespace in which the new table is to be created. If not specified, default_tablespace is consulted, or temp_tablespaces if the table is temporary.

query

A SELECT, TABLE, or VALUES command, or an EXECUTE command that runs a prepared SELECT, TABLE, or VALUES query.

WITH [NO ] DATA

This clause specifies whether or not the data produced by the query should be copied into the new table. If not, only the table structure is copied. The default is to copy the data.

Notes

This command is functionally similar to SELECT INTO, but it is preferred since it is less likely to be confused with other uses of the SELECT INTO syntax. Furthermore, CREATE TABLE AS offers a superset of the functionality offered by SELECT INTO.

Examples

Create a new table films_recent consisting of only recent entries from the table films:

CREATE TABLE films_recent AS
  SELECT * FROM films WHERE date_prod >= '2002-01-01';

To copy a table completely, the short form using the TABLE command can also be used:

CREATE TABLE films2 AS
  TABLE films;

Create a new temporary table films_recent, consisting of only recent entries from the table films, using a prepared statement. The new table will be dropped at commit:

PREPARE recentfilms(date) AS
  SELECT * FROM films WHERE date_prod > $1;
CREATE TEMP TABLE films_recent ON COMMIT DROP AS
  EXECUTE recentfilms('2002-01-01');

Compatibility

CREATE TABLE AS conforms to the SQL standard. The following are nonstandard extensions:

The standard requires parentheses around the subquery clause; in QHB, these parentheses are optional.
In the standard, the WITH [ NO ] DATA clause is required; in QHB it is optional.
QHB handles temporary tables in a way rather different from the standard; see CREATE TABLE for details.
The WITH clause is a QHB extension; storage parameters are not in the standard.
The QHB concept of tablespaces is not part of the standard. Hence, the clause TABLESPACE is an extension.