PHP Pdo\Pgsql::getNotify() Method: Usage and Examples

Fetches a pending PostgreSQL LISTEN/NOTIFY event as an array or false.

The objective is to understand the behavior and operational limits, not only the method name.

What It Does

Fetches a pending PostgreSQL LISTEN/NOTIFY event as an array or false.

Syntax and Return Value

Pdo\Pgsql::getNotify(...)

The return value and exceptional cases depend on the call described here: LISTEN on a channel first; timeout is measured in milliseconds, and no pending message returns false.

Requirements: install and enable the corresponding PHP driver or extension and configure the service before running the examples.

The driver-specific PDO subclasses are available starting with PHP 8.4, except setAuthorizer, which starts with PHP 8.5.

Example 1: Basic Use

A separate PostgreSQL session must issue NOTIFY inventory_events for this listener to receive an event.

<?php
$pdo = PDO::connect("pgsql:host=" . (getenv("DB_HOST") ?: "127.0.0.1") . ";dbname=" . (getenv("DB_NAME") ?: "demo"), getenv("DB_USER"), getenv("DB_PASSWORD"));
$pdo->exec("LISTEN inventory_events");
$notification = $pdo->getNotify(PDO::FETCH_ASSOC, 300);
if ($notification === false) { echo "No event received"; } else { echo json_encode($notification); }

Example 2: A Second Scenario

A separate PostgreSQL session must issue NOTIFY inventory_events for this listener to receive an event.

<?php
$pdo = PDO::connect("pgsql:host=" . (getenv("DB_HOST") ?: "127.0.0.1") . ";dbname=" . (getenv("DB_NAME") ?: "demo"), getenv("DB_USER"), getenv("DB_PASSWORD"));
$pdo->exec("LISTEN inventory_events");
$notification = $pdo->getNotify(PDO::FETCH_ASSOC, 400);
if ($notification === false) { echo "No event received"; } else { echo json_encode($notification); }

Example 3: Practical Checks

A separate PostgreSQL session must issue NOTIFY inventory_events for this listener to receive an event.

<?php
$pdo = PDO::connect("pgsql:host=" . (getenv("DB_HOST") ?: "127.0.0.1") . ";dbname=" . (getenv("DB_NAME") ?: "demo"), getenv("DB_USER"), getenv("DB_PASSWORD"));
$pdo->exec("LISTEN inventory_events");
$notification = $pdo->getNotify(PDO::FETCH_ASSOC, 500);
if ($notification === false) { echo "No event received"; } else { echo json_encode($notification); }

Important Behavior and Edge Cases

LISTEN on a channel first; timeout is measured in milliseconds, and no pending message returns false.

For production use, also account for error handling, data validation, resource limits and environment-specific driver behavior.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Fetches a pending PostgreSQL LISTEN/NOTIFY event as an array or false.
• LISTEN on a channel first; timeout is measured in milliseconds, and no pending message returns false.
• pg_get_notify provides similar notifications through the pgsql extension.

Choose this API or pattern when its exact semantics match your task, and verify the result against the database driver and runtime used by your application.