query-analysis.md

Query Analysis

Analyze query performance using EXPLAIN.

EXPLAIN

MySQL

$result = $db->find()
    ->from('users')
    ->where('email', 'user@example.com')
    ->explain();

// Returns execution plan
/*
Array
(
    [0] => Array
        (
            [id] => 1
            [select_type] => SIMPLE
            [table] => users
            [type] => ref
            [possible_keys] => email
            [key] => email
            [key_len] => 203
            [ref] => const
            [rows] => 1
            [Extra] => Using where
        )
)
*/

PostgreSQL

$result = $db->find()
    ->from('users')
    ->where('email', 'user@example.com')
    ->explain();

// Returns query plan with nodes

EXPLAIN ANALYZE

// PostgreSQL only
$result = $db->find()
    ->from('users')
    ->where('email', 'user@example.com')
    ->explainAnalyze();

// Returns actual execution time

DESCRIBE

Describe Table

$columns = $db->find()
    ->from('users')
    ->describe();

// Returns column information
/*
Array
(
    [0] => Array
        (
            [Field] => id
            [Type] => int(11)
            [Null] => NO
            [Key] => PRI
            [Default] => NULL
            [Extra] => auto_increment
        )
    ...
)
*/

Describe Index

$indexes = $db->rawQuery('SHOW INDEX FROM users');

Performance Tips

Check Index Usage

$result = $db->find()
    ->from('users')
    ->where('email', 'user@example.com')
    ->explain();

if ($result[0]['key'] === null) {
    echo "No index used!";
}

Analyze Slow Queries

// Enable query log
$db->enableQueryLog();

$users = $db->find()
    ->from('users')
    ->join('profiles', 'profiles.user_id', 'users.id')
    ->get();

$log = $db->getQueryLog();

foreach ($log as $query) {
    echo $query['sql'] . "\n";
    echo "Time: " . $query['time'] . "ms\n";
}

Next Steps

• Performance - Query optimization
• Common Pitfalls - Mistakes to avoid
• Troubleshooting - Common issues