10.3. Zend_Db_Profiler

Zend_Db_Profiler can be enabled to allow profiling of queries. Profiles include the queries processed by the adapter as well as elapsed time to run the queries, allowing inspection of the queries that have been performed without needing to add extra debugging code to classes. Advanced usage also allows the developer to filter which queries are profiled.

Enable the profiler by either passing a directive to the adapter constructor, or by asking the adapter to enable it later.

$params = array(
    'host'     => '127.0.0.1',
    'username' => 'webuser',
    'password' => 'xxxxxxxx',
    'dbname'   => 'test'
    'profiler' => true  // turn on profiler
                        // set to false to disable (disabled by default)
);

$db = Zend_Db::factory('PDO_MYSQL', $params);

// turn off profiler:
$db->getProfiler()->setEnabled(false);

// turn on profiler:
$db->getProfiler()->setEnabled(true);

        

The value of the 'profiler' option is flexible. It is interpreted differently depending on its type. Most often, you should use a simple boolean value, but other types enable you to customize the profiler behavior.

A boolean argument sets the profiler to enabled if it is a true value, or disabled if false. The profiler class is the adapter's default profiler class, Zend_Db_Profiler.

$params['profiler'] = true;
$db = Zend_Db::factory('PDO_MYSQL', $params);

            

An instance of a profiler object makes the adapter use that object. The object type must be Zend_Db_Profiler or a subclass thereof. Enabling the profiler is done separately.

$profiler = MyProject_Db_Profiler();
$profiler->setEnabled(true);
$params['profiler'] = $profiler;
$db = Zend_Db::factory('PDO_MYSQL', $params);

            

The argument can be an associative array containing any or all of the keys 'enabled', 'instance', and 'class'. The 'enabled' and 'instance' keys correspond to the boolean and instance types documented above. The 'class' key is used to name a class to use for a custom profiler. The class must be Zend_Db_Profiler or a subclass. The class is instantiated with no constructor arguments. The 'class' option is ignored when the 'instance' option is supplied.

$params['profiler'] = array(
    'enabled' => true,
    'class'   => 'MyProject_Db_Profiler'
);
$db = Zend_Db::factory('PDO_MYSQL', $params);

            

Finally, the argument can be an object of type Zend_Config containing properties, which are treated as the array keys described above. For example, a file "config.ini" might contain the following data:

[main]
db.profiler.class   = "MyProject_Db_Profiler"
db.profiler.enabled = true

            

This configuration can be applied by the following PHP code:

$config = new Zend_Config_Ini('config.ini', 'main');
$params['profiler'] = $config->db->profiler;
$db = Zend_Db::factory('PDO_MYSQL', $params);

            

The 'instance' property may be used as in the following:

$profiler = new MyProject_Db_Profiler();
$profiler->setEnabled(true);
$configData = array(
    'instance' => $profiler
    );
$config = new Zend_Config($configData);
$params['profiler'] = $config;
$db = Zend_Db::factory('PDO_MYSQL', $params);

            

At any point, grab the profiler using the adapter's getProfiler() method:

$profiler = $db->getProfiler();

        

This returns a Zend_Db_Profiler object instance. With that instance, the developer can examine your queries using a variety of methods:

The return value of getLastQueryProfile() and the individual elements of getQueryProfiles() are Zend_Db_Profiler_Query objects, which provide the ability to inspect the individual queries themselves:

The information Zend_Db_Profiler provides is useful for profiling bottlenecks in applications, and for debugging queries that have been run. For instance, to see the exact query that was last run:

$query = $profiler->getLastQueryProfile();

echo $query->getQuery();

        

Perhaps a page is generating slowly; use the profiler to determine first the total number of seconds of all queries, and then step through the queries to find the one that ran longest:

$totalTime    = $profiler->getTotalElapsedSecs();
$queryCount   = $profiler->getTotalNumQueries();
$longestTime  = 0;
$longestQuery = null;

foreach ($profiler->getQueryProfiles() as $query) {
    if ($query->getElapsedSecs() > $longestTime) {
        $longestTime  = $query->getElapsedSecs();
        $longestQuery = $query->getQuery();
    }
}

echo 'Executed ' . $queryCount . ' queries in ' . $totalTime . 
     ' seconds' . "\n";
echo 'Average query length: ' . $totalTime / $queryCount .
     ' seconds' . "\n";
echo 'Queries per second: ' . $queryCount / $totalTime . "\n";
echo 'Longest query length: ' . $longestTime . "\n";
echo "Longest query: \n" . $longestQuery . "\n";

        

In addition to query inspection, the profiler also allows the developer to filter which queries get profiled. The following methods operate on a Zend_Db_Profiler instance:

// Only profile queries that take at least 5 seconds:
$profiler->setFilterElapsedSecs(5);

// Profile all queries regardless of length:
$profiler->setFilterElapsedSecs(null);

            

// profile only SELECT queries
$profiler->setFilterQueryType(Zend_Db_Profiler::SELECT);

// profile SELECT, INSERT, and UPDATE queries
$profiler->setFilterQueryType(Zend_Db_Profiler::SELECT |
                              Zend_Db_Profiler::INSERT |
                              Zend_Db_Profiler::UPDATE);

// profile DELETE queries
$profiler->setFilterQueryType(Zend_Db_Profiler::DELETE);

// Remove all filters
$profiler->setFilterQueryType(null);

            

// Retrieve only SELECT query profiles
$profiles = $profiler->getQueryProfiles(Zend_Db_Profiler::SELECT);

// Retrieve only SELECT, INSERT, and UPDATE query profiles
$profiles = $profiler->getQueryProfiles(Zend_Db_Profiler::SELECT |
                                        Zend_Db_Profiler::INSERT |
                                        Zend_Db_Profiler::UPDATE);

// Retrieve DELETE query profiles
$profiles = $profiler->getQueryProfiles(Zend_Db_Profiler::DELETE);

            

A Specialized Profiler is an object that inherits from Zend_Db_Profiler. Specialized Profilers treat profiling information in specific ways.

// In your bootstrap file

$profiler = new Zend_Db_Profiler_Firebug('All DB Queries');
$profiler->setEnabled(true);

// Attach the profiler to your db adapter
$db->setProfiler($profiler)

// Dispatch your front controller

// All DB queries in your model, view and controller
// files will now be profiled and sent to Firebug

        

$profiler = new Zend_Db_Profiler_Firebug('All DB Queries');
$profiler->setEnabled(true);

// Attach the profiler to your db adapter
$db->setProfiler($profiler)

$request  = new Zend_Controller_Request_Http();
$response = new Zend_Controller_Response_Http();
$channel  = Zend_Wildfire_Channel_HttpHeaders::getInstance();
$channel->setRequest($request);
$channel->setResponse($response);

// Start output buffering
ob_start();

// Now you can run your DB queries to be profiled

// Flush profiling data to browser
$channel->flush();
$response->sendHeaders();