pg_get_notify

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

    pg_get_notify — Gets SQL NOTIFY message

    Description

    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.

    Parameters

    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.

    Return Values

    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.

    Changelog

    Version Description
    8.1.0 The connection parameter expects an PgSql\Connection instance now; previously, a resource was expected.

    Examples

    Example #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);
    }
    ?>

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    User Contributed Notes 2 notes

    up
    7
    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)
    up
    0
    david at frankieandshadow dot com
    3 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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