ALTER FOREIGN TABLE

Function

ALTER FOREIGN TABLE modifies a foreign table.

Syntax

AlterForeignTable ::= ALTER FOREIGN TABLE [ IF EXISTS ]  table_name
    OPTIONS ( {[ ADD | SET | DROP ] option ['value']}[, ... ]);

AlterForeignTable ::= ALTER FOREIGN TABLE [ IF EXISTS ] table_name
    ALTER column_name OPTIONS;

Parameter Description

• table_name

  Specifies the name of an existing foreign table to be modified.

  Value range: an existing foreign table name.

• option

  Specifies the option of a foreign table or foreign table column to be modified. ADD, SET, and DROP are operations to be performed. If no operation is set explicitly, the default value ADD is used. The option name must be unique (although table options and table column options can share the same name). The name and value of the option are also validated by a class library of a foreign data wrapper.

  • Options supported by oracle_fdw are as follows:

    • table

      Name of a table on the Oracle server. The value must be the same as the table name recorded in the Oracle system catalog. Generally, the value consists of uppercase letters.

    • schema

      Schema (or owner) corresponding to the table. The value must be the same as the table name recorded in the Oracle system catalog. Generally, the value consists of uppercase letters.

  • Options supported by mysql_fdw are as follows:

    • dbname

      Name of the MySQL database.

    • table_name

      Name of a table in the MySQL database.

  • Options supported by postgres_fdw are as follows:

    • schema_name

      Schema name of a remote server. If this option is not specified, the schema name of the foreign table is used as the schema name of the remote server.

    • table_name

      Table name of a remote server. If this option is not specified, the name of the foreign table is used as the table name of the remote server.

    • column_name

      Column name of a table on a remote server. If this option is not specified, the column name of the foreign table is used as the column name of a table on a remote server.

• Options supported by file_fdw are as follows:

  • filename

    File to be read. This parameter is mandatory and must be an absolute path.

  • format

    File format of the remote server, which is the same as the FORMAT option in the COPY statement. The value can be text, csv, binary, or fixed.

  • header

    Specifies whether a specified file has a header, which is the same as the HEADER option of the COPY statement.

  • delimiter

    File delimiter, which is the same as the DELIMITER option of the COPY statement.

  • quote

    Quote character of a file, which is the same as the QUOTE option of the COPY statement.

  • escape

    Escape character of a file, which is the same as the ESCAPE option of the COPY statement.

  • null

    Null string of a file, which is the same as the NULL option of the COPY statement.

  • encoding

    Encoding of a file, which is the same as the ENCODING option of the COPY statement.

  • force_not_null

    This is a Boolean option. If it is true, the value of the declared field cannot be an empty string. This option is the same as the FORCE_NOT_NULL option of the COPY statement.

  NOTE: For details about how to use file_fdw, see file_fdw.

• value

  Specifies the new value of option.

Helpful Links

CREATE FOREIGN TABLE，DROP FOREIGN TABLE