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download PDF document: dblink_fetch.3.pdf

DBLINK_FETCH(3) PostgreSQL 15.4 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); (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 15.4 2023 DBLINK_FETCH(3)