perl use of cursors and fetch forward

Started by John Frankabout 25 years ago3 messagesgeneral
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#1John Frank
jrf@segovia.mit.edu

Can someone tell me how to use Postgres cursors through perl? A sample is
below. Is there some way to keep the transaction active between
$conn-exec calls?

#!/usr/local/bin/perl
use Pg;
my $conn = Pg::connectdb("dbname = test");

my $result = $conn->exec("begin work; declare c1 cursor for select fld1
from tbl1 ; ");

$result = $conn->exec("fetch forward 1 in c1;");
print "Hurray, I fetched a row: " . $result->fetchrow . "\n";

$result = $conn->exec("end work;");

jrf@roog:~/$ perl test_cursor.pl
NOTICE: PerformPortalFetch: portal "c1" not found
Hurray, I fetched a row:
NOTICE: COMMIT: no transaction in progress
jrf@roog:~/$

#2John Frank
jrf@segovia.mit.edu
In reply to: John Frank (#1)
Re: perl use of cursors and fetch forward

dooh. never mind.

this works if the "begin work;" and "declare ...;" are in separate exec
requests.

On Mon, 29 Jan 2001, John Frank wrote:

Show quoted text

Can someone tell me how to use Postgres cursors through perl? A sample is
below. Is there some way to keep the transaction active between
$conn-exec calls?

#!/usr/local/bin/perl
use Pg;
my $conn = Pg::connectdb("dbname = test");

my $result = $conn->exec("begin work; declare c1 cursor for select fld1
from tbl1 ; ");

$result = $conn->exec("fetch forward 1 in c1;");
print "Hurray, I fetched a row: " . $result->fetchrow . "\n";

$result = $conn->exec("end work;");

jrf@roog:~/$ perl test_cursor.pl
NOTICE: PerformPortalFetch: portal "c1" not found
Hurray, I fetched a row:
NOTICE: COMMIT: no transaction in progress
jrf@roog:~/$

#3Tom Lane
tgl@sss.pgh.pa.us
In reply to: John Frank (#2)
Re: Re: perl use of cursors and fetch forward

John Frank <jrf@segovia.mit.edu> writes:

this works if the "begin work;" and "declare ...;" are in separate exec
requests.

This is fixed for 7.1. The problem in 7.0 is that the check for "are we
inside a transaction block?" is done at the wrong time, ie, during
initial parsing of the query string ...

regards, tom lane