DBLINK_FETCH(3)                   PostgreSQL 12.3 Documentation                   DBLINK_FETCH(3)



NAME
       dblink_fetch - returns rows from an open cursor in a remote database

SYNOPSIS
       dblink_fetch(text cursorname, int howmany [, bool fail_on_error]) returns setof record
       dblink_fetch(text connname, text cursorname, int howmany [, bool fail_on_error]) returns setof record

DESCRIPTION
       dblink_fetch fetches rows from a cursor previously established by dblink_open.

ARGUMENTS
       connname
           Name of the connection to use; omit this parameter to use the unnamed connection.

       cursorname
           The name of the cursor to fetch from.

       howmany
           The maximum number of rows to retrieve. The next howmany rows are fetched, starting at
           the current cursor position, moving forward. Once the cursor has reached its end, no
           more rows are produced.

       fail_on_error
           If true (the default when omitted) then an error thrown on the remote side of the
           connection causes an error to also be thrown locally. If false, the remote error is
           locally reported as a NOTICE, and the function returns no rows.

RETURN VALUE
       The function returns the row(s) fetched from the cursor. To use this function, you will
       need to specify the expected set of columns, as previously discussed for dblink.

NOTES
       On a mismatch between the number of return columns specified in the FROM clause, and the
       actual number of columns returned by the remote cursor, an error will be thrown. In this
       event, the remote cursor is still advanced by as many rows as it would have been if the
       error had not occurred. The same is true for any other error occurring in the local query
       after the remote FETCH has been done.

EXAMPLES
           SELECT dblink_connect('dbname=postgres options=-csearch_path=');
            dblink_connect
           ----------------
            OK
           (1 row)

           SELECT dblink_open('foo', 'select proname, prosrc from pg_proc where proname like ''bytea%''');
            dblink_open
           -------------
            OK
           (1 row)

           SELECT * FROM dblink_fetch('foo', 5) AS (funcname name, source text);
            funcname |  source
           ----------+----------
            byteacat | byteacat
            byteacmp | byteacmp
            byteaeq  | byteaeq
            byteage  | byteage
            byteagt  | byteagt
           (5 rows)

           SELECT * FROM dblink_fetch('foo', 5) AS (funcname name, source text);
            funcname  |  source
           -----------+-----------
            byteain   | byteain
            byteale   | byteale
            bytealike | bytealike
            bytealt   | bytealt
            byteane   | byteane
           (5 rows)

           SELECT * FROM dblink_fetch('foo', 5) AS (funcname name, source text);
             funcname  |   source
           ------------+------------
            byteanlike | byteanlike
            byteaout   | byteaout
           (2 rows)

           SELECT * FROM dblink_fetch('foo', 5) AS (funcname name, source text);
            funcname | source
           ----------+--------
           (0 rows)



PostgreSQL 12.3                                2020                               DBLINK_FETCH(3)