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CREATE SERVER

Defines a new foreign server.

Synopsis

CREATE SERVER <server_name> [ TYPE '<server_type>' ] [ VERSION '<server_version>' ]
    FOREIGN DATA WRAPPER <fdw_name>
    [ OPTIONS ( [ mpp_execute { 'master' | 'any' | 'all segments' } [, ] ]
                [ num_segments '<num>' [, ] ]
                [ <option> '<value>' [, ... ]] ) ]

Description

CREATE SERVER defines a new foreign server. The user who defines the server becomes its owner. A foreign server typically encapsulates connection information that a foreign data wrapper uses to access an external data source. Additional user-specific connection information may be specified by means of user mappings. Creating a server requires the USAGE privilege on the foreign data wrapper specified.

Parameters

Parameter Description

server_name

The name of the foreign server to create. The server name must be unique within the database

server_type

Optional server type, potentially useful to foreign data wrappers

server_version

Optional server version, potentially useful to foreign data wrappers

fdw_name

Name of the foreign data wrapper that manages the server

OPTIONS ( <option> '<value>' [, …​ ] )

The options for the new foreign server. The options typically define the connection details of the server, but the actual names and values are dependent upon the server’s foreign data wrapper

mpp_execute { 'master' | 'any' | 'all segments' }

A Greengage DB-specific option that identifies the host from which the foreign data wrapper reads or writes data:

  • master (default) — read or write data from the master host.

  • any — read data from either the master host or any one segment, depending on which path costs less.

  • all segments — read or write data from all segments. To support this option value, the foreign data wrapper should have a policy that matches the segments to data. Greengage DB supports parallel writes to foreign tables only when you set mpp_execute 'all segments'.

Support for the foreign server mpp_execute option, and the specific modes, is foreign data wrapper-specific.

The mpp_execute option can be specified in multiple commands: CREATE FOREIGN TABLE, CREATE SERVER, and CREATE FOREIGN DATA WRAPPER. The foreign table setting takes precedence over the foreign server setting, followed by the foreign data wrapper setting

num_segments '<num>'

When mpp_execute is set to 'all segments', the Greengage DB-specific num_segments option identifies the number of query executors that Greengage DB spawns on the source Greengage DB cluster. If you do not provide a value, num defaults to the number of segments in the source cluster.

Support for the foreign server num_segments option is foreign data wrapper-specific

Notes

When using the dblink module, you can use the foreign server name as an argument of the dblink_connect() function to provide the connection parameters. You must have the USAGE privilege on the foreign server to use it in this manner.

Examples

Create a foreign server named myserver that uses the foreign data wrapper named pgsql and includes connection options:

CREATE SERVER myserver FOREIGN DATA WRAPPER pgsql
    OPTIONS (host 'foo', dbname 'foodb', port '5432');

Compatibility

CREATE SERVER conforms to ISO/IEC 9075-9 (SQL/MED).

See also

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CREATE SEQUENCE
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CREATE TABLE