![]() Only superusers may create or modify user mappings with the sslcert or sslkey settings. If both are present, the user mapping setting overrides the connection setting. ![]() Sslkey and sslcert - these may appear in either or both a connection and a user mapping. See postgres_fdw.application_name for details.įallback_application_name (always set to postgres_fdw) Unlike libpq, postgres_fdw allows application_name to include “ escape sequences”. If both are present, postgres_fdw.application_name overrides the connection setting. User, password and sslpassword (specify these in a user mapping, instead, or use a service file)Ĭlient_encoding (this is automatically set from the local server encoding)Īpplication_name - this may appear in either or both a connection and postgres_fdw.application_name. Matching of columns to the remote table is by name, not position. Note that a foreign table can be declared with fewer columns, or with a different column order, than its underlying remote table has. Although postgres_fdw is currently rather forgiving about performing data type conversions at need, surprising semantic anomalies may arise when types or collations do not match, due to the remote server interpreting query conditions differently from the local server. It is generally recommended that the columns of a foreign table be declared with exactly the same data types, and collations if applicable, as the referenced columns of the remote table. Note also that postgres_fdw supports row movement invoked by UPDATE statements executed on partitioned tables, but it currently does not handle the case where a remote partition chosen to insert a moved row into is also an UPDATE target partition that will be updated elsewhere in the same command. However, the ON CONFLICT DO NOTHING clause is supported, provided a unique index inference specification is omitted. Note that postgres_fdw currently lacks support for INSERT statements with an ON CONFLICT DO UPDATE clause. ![]() Note that the ONLY option specified in SELECT, UPDATE, DELETE or TRUNCATE has no effect when accessing or modifying the remote table. (Of course, the remote user you have specified in your user mapping must have privileges to do these things.) You can also modify the remote table using INSERT, UPDATE, DELETE, COPY, or TRUNCATE. Now you need only SELECT from a foreign table to access the data stored in its underlying remote table. You can, however, use table and/or column names different from the remote table's, if you specify the correct remote names as options of the foreign table object. The columns of the foreign table must match the referenced remote table. Specify the remote user name and password to use as user and password options of the user mapping.Ĭreate a foreign table, using CREATE FOREIGN TABLE or IMPORT FOREIGN SCHEMA, for each remote table you want to access. Specify connection information, except user and password, as options of the server object.Ĭreate a user mapping, using CREATE USER MAPPING, for each database user you want to allow to access each foreign server. Install the postgres_fdw extension using CREATE EXTENSION.Ĭreate a foreign server object, using CREATE SERVER, to represent each remote database you want to connect to.
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