CREATE SERVER

Defines a new foreign server.

Synopsis

CREATE SERVER [ IF NOT EXISTS ] <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

IF NOT EXISTS

: Do not throw an error if a server with the same name already exists. LightDB-A Database issues a notice in this case. Note that there is no guarantee that the existing server is anything like the one that would have been created.

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

-   `master` \(the default\)—Read or write data from the coordinator host.
-   `any`—Read data from either the coordinator 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.

> **Note** LightDB-A Database 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 LightDB-A Database-specific num_segments option identifies the number of query executors that LightDB-A Database spawns on the source LightDB-A Database 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 (see dblink), 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 a foreign-data wrapper named gpfdw1 and includes connection options:

CREATE SERVER myserver FOREIGN DATA WRAPPER gpfdw1 
    OPTIONS (host 'foo', dbname 'foodb', port '5432');

Compatibility

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