(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)
pg_get_result — Lit un résultat PostgreSQL asynchrone
pg_get_result() récupère l'instance PgSql\Result d'une requête asynchrone exécutée par pg_send_query(), pg_send_query_params(), ou pg_send_execute().
pg_send_query() et les autres fonctions de requête asynchrone peuvent envoyer plusieurs requêtes à un serveur PostgreSQL et pg_get_result() est utilisé pour obtenir chaque résultat de requête, un par un.
Une instance de PgSql\Result, ou false s'il n'y a
plus de résultat disponible.
| Version | Description |
|---|---|
| 8.1.0 | Retourne désormais une instance de PgSql\Result instance ; auparavant, une ressource était retourné. |
| 8.1.0 |
Le paramètre connection attend désormais une instance de
PgSql\Connection ; auparavant, une ressource était attendu.
|
Exemple #1 Exemple avec pg_get_result()
<?php
$dbconn = pg_connect("dbname=publisher") or die("Connexion impossible");
if (!pg_connection_busy($dbconn)) {
pg_send_query($dbconn, "select * from auteurs; select count(*) from auteurs;");
}
$res1 = pg_get_result($dbconn);
echo "Premier appel à pg_get_result(): $res1\n";
$rows1 = pg_num_rows($res1);
echo "$res1 a $rows1 enregistrements\n\n";
$res2 = pg_get_result($dbconn);
echo "Second appel à pg_get_result(): $res2\n";
$rows2 = pg_num_rows($res2);
echo "$res2 a $rows2 enregistrements\n";
?>L'exemple ci-dessus va afficher :
Premier appel à pg_get_result(): Resource id #3 Resource id #3 a 3 enregistrements Second appel à pg_get_result(): Resource id #4 Resource id #4 a 1 enregistrements
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.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.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);
?>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.