pg_get_notify

(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)

pg_get_notify — Gets SQL NOTIFY message

Descripción

pg_get_notify(PgSql\Connection $connection, int $mode = PGSQL_ASSOC): array|false

pg_get_notify() gets notifications generated by a NOTIFY SQL command. To receive notifications, the LISTEN SQL command must be issued.

Parámetros

connection: An PgSql\Connection instance.
mode: An optional parameter that controls how the returned array is indexed. mode is a constant and can take the following values: PGSQL_ASSOC, PGSQL_NUM and PGSQL_BOTH. Using PGSQL_NUM, the function will return an array with numerical indices, using PGSQL_ASSOC it will return only associative indices while PGSQL_BOTH will return both numerical and associative indices.

Valores devueltos

An array containing the NOTIFY message name and backend PID. If supported by the server, the array also contains the server version and the payload. Otherwise if no NOTIFY is waiting, then false is returned.

Historial de cambios

Versión	Descripción
8.1.0	The `connection` parameter expects an PgSql\Connection instance now; previously, a recurso was expected.

Ejemplos

Ejemplo #1 PostgreSQL NOTIFY message

<?php 
$conn = pg_pconnect("dbname=publisher");
if (!$conn) {
  echo "An error occurred.\n";
  exit;
}

// Listen 'author_updated' message from other processes
pg_query($conn, 'LISTEN author_updated;');
$notify = pg_get_notify($conn);
if (!$notify) {
  echo "No messages\n";
} else {
  print_r($notify);
}
?>

Ver también

pg_get_pid() - Obtiene la ID del proceso del backend

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User Contributed Notes 2 notes

down

glococo at gmail dot com ¶

6 years ago


Instant yet Simple PHP notification with HTML5 Server-Sent Events

sse.php
<?php
$dbconn = new PDO("pgsql:host=localhost;dbname=mydb", "pduser", "userpass");
$dbconn->exec('LISTEN "channel_name"');   // those doublequotes are very important

header("X-Accel-Buffering: no"); // disable ngnix webServer buffering
header("Content-Type: text/event-stream");
header("Cache-Control: no-cache");
ob_end_flush();  // close PHP output buffering
$inc=0;

while (1) {
  $result = "";
  // wait for one Notify 10seconds instead of using sleep(10)
  $result = $dbconn->pgsqlGetNotify(PDO::FETCH_ASSOC, 10000); 

  if ( $result ) { 
        echo "id: $inc\ndata: ".stripslashes(json_encode($result))."\n\n";
        $inc++;
  }

  flush();
}
?>

Tested with HTML+JS sample file from Mozilla web site (ssedemo.php)

down

david at frankieandshadow dot com ¶

2 years ago


It appears that pg_get_notify does not distinguish between no message waiting and a failure when checking - both seem to return FALSE.

I had to add a pg_check_connection(...) before pg_get_notify to check the connection is still alive (it's quite likely to be a long-standing connection with pg_get_notify as you'll be polling waiting for something to happen). In my case the remote database server had a hiccup, and without pg_check_connection the listeners failed to notice, so never saw later notifications.

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