There is no way to poll/wait for a notification to come in. You either have to enter a busy loop or sleep. Both options are horrible. It would be nice for PHP to provide access to PQsocket so one could select() on the socket connection. This is how it's done from C or Perl.
pg_get_result
(PHP 4 >= 4.2.0, PHP 5, PHP 7)
pg_get_result — Gibt asynchrone Abfrageergebnisse zurück
Beschreibung
pg_get_result
([ resource
$connection
] ) : resourcepg_get_result() gibt die Ergebniskennung einer asynchronen Abfrage zurück, die mit pg_send_query(), pg_send_query_params() oder pg_send_execute() an den Datenbankserver gesendet wurde.
Mit pg_send_query() und auch den anderen asynchronen Abfragefunktionen können mehrere Abfragen an den Server geschickt werden. Deren Ergebnisse können mit pg_get_result() nacheinander abgefragt werden.
Parameter-Liste
-
connection -
PostgreSQL Verbindungskennung.
Rückgabewerte
Die Ergebniskennung als resource or FALSE, falls es
keine Ergebnisse gibt.
Beispiele
Beispiel #1 pg_get_result() Beispiel
<?php
$dbconn = pg_connect("dbname=publisher") or die("Verbindungsaufbau fehlgeschlagen");
if (!pg_connection_busy($dbconn)) {
pg_send_query($dbconn, "select * from authors; select count(*) from authors;");
}
$res1 = pg_get_result($dbconn);
echo "Der erste Aufruf von pg_get_result(): $res1\n";
$rows1 = pg_num_rows($res1);
echo "$res1 hat $rows1 Zeilen\n\n";
$res2 = pg_get_result($dbconn);
echo "Der zweite Aufruf von pg_get_result(): $res2\n";
$rows2 = pg_num_rows($res2);
echo "$res2 hat $rows2 Zeilen\n";
?>
Das oben gezeigte Beispiel erzeugt folgende Ausgabe:
Der erste Aufruf von pg_get_result(): Resource id #3 Resource id #3 hat 3 Zeilen Der zweite Aufruf von pg_get_result(): Resource id #4 Resource id #4 hat 1 Zeilen
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User Contributed Notes 4 notes
william at 25thandClement dot com ¶
14 years ago
Ondej Bouda ¶
3 years ago
It might seem that after calling pg_get_result() upon sending just a single query, the connection will not be busy. The correct way is, though, to call extra pg_get_result() in a loop until it returns false [1].
<?php
$conn = pg_connect('...', PGSQL_CONNECT_FORCE_NEW);
for ($i = 0; $i < 10000; $i++) {
$query = 'erroneous query';
if (pg_connection_busy($conn)) {
fprintf(STDERR, "Connection is busy\n");
exit(1);
}
pg_send_query($conn, $query);
$res = pg_get_result($conn);
if ($res === false) {
fprintf(STDERR, "A result was expected\n");
exit(1);
}
/* The following does not seem necessary for good queries, but is vital for erroneous queries.
Commenting the loop out leads to this script fail with the "Connection is busy" error. */
while (pg_get_result($conn));
// result processing...
}
?>
See http://www.postgresql.org/message-id/flat/gtitqq$26l3$1@news.hub.org#gtitqq$26l3$1@news.hub.org and https://bugs.php.net/bug.php?id=52750 for detailed information.
[1] Or, even better, use an asynchronous connection since PHP 5.6.
gullevek at gullevek dot org ¶
5 years ago
To have a a simple wait output with async queries you can use the pg_connection_busy command:
<?php
$dbh = pg_connect("host=XXX user=XXX password=XXX dbname=XXX");
if (!$dbh)
{
print "Failed to connect";
exit;
}
$query = "SELECT pg_sleep(10)";
if (!pg_connection_busy($dbh))
{
$sent = pg_send_query($dbh, $query);
print "Sent query, waiting: ";
while (pg_connection_busy($dbh)
{
print ".";
flush();
}
$res = pg_get_result($dbh);
print "<br>"; // or \n
print "Result is: $res";
}
pg_close($dbh);
?>
Marko Tiikkaja ¶
10 years ago
william at 25thandClement dot com said: "There is no way to poll/wait for a notification to come in. .."
Yes, there is. If there is a query in progress, pg_get_result() will block and return the result of that query when it's complete.
