EVOLUTION-MANAGER

Edit File: dblink_fetch.3

'\" t
.\"     Title: dblink_fetch
.\"    Author: The PostgreSQL Global Development Group
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 2025
.\"    Manual: PostgreSQL 14.18 Documentation
.\"    Source: PostgreSQL 14.18
.\"  Language: English
.\"
.TH "DBLINK_FETCH" "3" "2025" "PostgreSQL 14.18" "PostgreSQL 14.18 Documentation"
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.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
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.\" * set default formatting
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.nh
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.\" * MAIN CONTENT STARTS HERE *
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.SH "NAME"
dblink_fetch \- returns rows from an open cursor in a remote database
.SH "SYNOPSIS"
.sp
.nf
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
.fi
.SH "DESCRIPTION"
.PP
\fBdblink_fetch\fR
fetches rows from a cursor previously established by
\fBdblink_open\fR\&.
.SH "ARGUMENTS"
.PP
\fIconnname\fR
.RS 4
Name of the connection to use; omit this parameter to use the unnamed connection\&.
.RE
.PP
\fIcursorname\fR
.RS 4
The name of the cursor to fetch from\&.
.RE
.PP
\fIhowmany\fR
.RS 4
The maximum number of rows to retrieve\&. The next
\fIhowmany\fR
rows are fetched, starting at the current cursor position, moving forward\&. Once the cursor has reached its end, no more rows are produced\&.
.RE
.PP
\fIfail_on_error\fR
.RS 4
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\&.
.RE
.SH "RETURN VALUE"
.PP
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
\fBdblink\fR\&.
.SH "NOTES"
.PP
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
\fBFETCH\fR
has been done\&.
.SH "EXAMPLES"
.sp
.if n \{\
.RS 4
.\}
.nf
SELECT dblink_connect(\*(Aqdbname=postgres options=\-csearch_path=\*(Aq);
 dblink_connect
\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
 OK
(1 row)

SELECT dblink_open(\*(Aqfoo\*(Aq, \*(Aqselect proname, prosrc from pg_proc where proname like \*(Aq\*(Aqbytea%\*(Aq\*(Aq\*(Aq);
 dblink_open
\-\-\-\-\-\-\-\-\-\-\-\-\-
 OK
(1 row)

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

SELECT * FROM dblink_fetch(\*(Aqfoo\*(Aq, 5) AS (funcname name, source text);
 funcname | source
\-\-\-\-\-\-\-\-\-\-+\-\-\-\-\-\-\-\-
(0 rows)
.fi
.if n \{\
.RE
.\}