pg_get_notify

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

pg_get_notify — Gets SQL NOTIFY message

Опис

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.

Параметри

connection: Примірник PgSql\Connection.
mode: Необов'язковий параметр, яким вказується спосіб індексування масиву (array). mode може мати значення однієї з констант: PGSQL_ASSOC, PGSQL_NUM або PGSQL_BOTH. Якщо задано PGSQL_NUM, то функція поверне масив з числовими індексами; якщо PGSQL_ASSOC, то з асоціативними індексами; якщо PGSQL_BOTH, то і з числовими, і з асоціативними індексами.

Значення, що повертаються

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.

Журнал змін

Версія	Опис
8.1.0	Тепер параметр `connection` має бути примірником PgSql\Connection. Раніше очікувався resource.

Приклади

Приклад #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);
}
?>

Прогляньте також

pg_get_pid() - Gets the backend's process ID

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User Contributed Notes 2 notes

down

glococo at gmail dot com ¶

7 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 ¶

4 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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