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DBLINK_FETCH(3) PostgreSQL 16.5 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)
2024 PostgreSQL 16.5