Use stmt_init for query cache optimization

When using PHP for database development, how to improve the performance of database queries has always been one of the important issues that developers are concerned about. Especially for frequently executed queries, it may be a lot of time to re-parse SQL statements every time. Fortunately, MySQL's mysqli extension provides the stmt_init function, which can help us perform query cache optimization, thereby improving performance.

1. Introduction to mysqli::stmt_init function

In PHP, mysqli provides an interface to interact with the MySQL database, and the stmt_init function is a method in the mysqli class that is used to initialize a statement object. It provides the necessary environment for subsequent query preparation and execution, and can effectively cache preprocessing statements, thereby reducing the repetitive parsing time of SQL statements.

2. Use mysqli::stmt_init to optimize query cache

When you create a preprocessing statement using mysqli::stmt_init , the MySQL database preprocesses and caches the SQL statements. In this way, even if the same query is executed multiple times, the database only needs to parse the SQL statement once, which can greatly improve the execution speed of the query.

3. How to use mysqli::stmt_init for query cache optimization

In PHP, the steps to use the mysqli::stmt_init function are very simple. Here is an example of query cache optimization using stmt_init :

 <?php
// Create a mysqli Instance and connect to the database
$mysqli = new mysqli("localhost", "username", "password", "database_name");

// Check if the connection is successful
if ($mysqli->connect_error) {
    die("Connection failed: " . $mysqli->connect_error);
}

// use stmt_init Initialize preprocessing statements
$stmt = $mysqli->stmt_init();

// Check whether the initialization is successful
if ($stmt) {
    // Prepare SQL Query
    $sql = "SELECT * FROM users WHERE email = ?";
    
    // Preprocessing SQL Query
    if ($stmt->prepare($sql)) {
        // Bind parameters
        $stmt->bind_param("s", $email);
        
        // 设置Query参数并执行Query
        $email = "user@m66.net";
        $stmt->execute();
        
        // 获取Query结果
        $result = $stmt->get_result();
        
        // 输出Query结果
        while ($row = $result->fetch_assoc()) {
            echo "User email: " . $row['email'] . "<br>";
            echo "Username: " . $row['name'] . "<br>";
        }
        
        // Close statement
        $stmt->close();
    } else {
        echo "Prepare SQL Query失败: " . $mysqli->error;
    }
} else {
    echo "Initialization statement failed: " . $mysqli->error;
}

// Close the database connection
$mysqli->close();
?>

4. Optimization effect and query cache

Through the above code, we can see the following important optimization points:

1. Reduce the number of SQL statement parsing times : MySQL preprocesses and caches SQL statements every time stmt_init and prepare are executed. In this way, when the same query is executed in the subsequent execution, there is no need to parse the SQL again, and directly obtain the execution plan from the cache, thereby reducing time overhead.

2. Improve query performance : Especially in the case of a large number of similar queries, the number of repeated parsing can be reduced by using preprocessing statements, thereby significantly improving the query performance of the database.

3. Parameter binding : Use bind_param to bind parameters to avoid repeated constructing of SQL statements, thereby improving the security and readability of the code.

5. Further optimization suggestions

Although mysqli::stmt_init can effectively improve query performance, we can also consider some other optimization methods:

• Cache result set : For frequently queried data, consider using a cache system (such as Redis or Memcached) to cache query results to avoid accessing the database every time.

• Index optimization : Ensure that the columns involved in the query have appropriate indexes in the database to speed up query operations.

• Batch processing query : For similar queries that are executed multiple times, you can consider batch execution of queries instead of individual executions each time.

6. Summary

Using mysqli::stmt_init for query cache optimization is an effective way to improve the performance of PHP applications. Through preprocessing statements and parameter binding, the number of SQL parsing can be reduced and the efficiency of database queries can be improved. Combining other optimization strategies, such as using cache and indexing, can further improve the overall performance of the application.