<?php

$db_host = '127.0.0.1';
$db_user = 'root';
$db_pass = '';
$db_name = 'mysql';

$conn = mysqli_connect($db_host, $db_user, $db_pass, $db_name);

/*
 * Regular queries are properly logged in performance_schema.events_statements_summary_by_digest
 * DIGEST_TEXT: SELECT * FROM `mysql` . `user` 
 */
//$conn->query('SELECT * FROM mysql.user');

/*
 * C API statements not logged
 * No entry created in performance_schema.events_statements_summary_by_digest
 */
$stmt = $conn->stmt_init();
$stmt->prepare('SELECT * FROM mysql.user');
$stmt->execute();

/*
 * The statement appears in `prepared_statement_instances` before closing it
 */
sleep(10);
$stmt->close();

?>