How to optimize queries of PHP and MySQL calculated fields and JSON data through indexes?

How to optimize queries of calculated fields and JSON data in PHP and MySQL through indexes?

Introduction:
In PHP and MySQL development, query requirements for calculated fields and JSON data are often involved. However, since both types of queries will bring high computational complexity and data processing complexity, they may lead to performance degradation if not optimized. This article will introduce how to optimize PHP and MySQL calculated fields and JSON data queries through indexes, and provide specific code examples.

1. Optimize the query of calculated fields
Calculated fields refer to the results obtained through a certain calculation method, rather than fields read directly from the database. In the development of PHP and MySQL, if the query of calculated fields is not optimized, it may cause performance degradation. The following are some methods to optimize calculated field queries:

1. Using MySQL's stored functions
   MySQL provides various built-in stored functions, such as SUM, AVG, COUNT, etc., these functions can be directly used in Calculate the value of the field in the database without taking out all the data and then calculating it. For example, to calculate the sum of a table you can use the SUM function instead of using a loop calculation in PHP. This can reduce the amount of data transmission and improve query efficiency. The following is a specific example:

$query = "SELECT SUM(price) AS total_price FROM products";
$result = mysqli_query($conn, $query);
$row = mysqli_fetch_assoc($result);
$total_price = $row['total_price'];

2. Using MySQL's calculated fields
   MySQL allows you to define calculated fields in query statements, and you can directly obtain the required calculation results through these calculated fields. . This can hand over the calculation work to the database engine and reduce the burden on the PHP code. For example, to calculate the sum and average of a table, you can use the following statement:

$query = "SELECT SUM(price) AS total_price, AVG(price) AS avg_price FROM products";
$result = mysqli_query($conn, $query);
$row = mysqli_fetch_assoc($result);
$total_price = $row['total_price'];
$avg_price = $row['avg_price'];

3. Use caching technology
   If the value of the calculated field does not change within a period of time, Consider using caching technology to store calculation results. When the calculated field needs to be queried, first check whether the value exists in the cache. If it exists, the result in the cache will be returned directly. Otherwise, the calculation will be performed and the result will be stored in the cache. This can reduce the number of queries and improve query efficiency. For example, use memcached to implement caching:

$memcache = new Memcache;
$memcache->connect('localhost', 11211);
$total_price = $memcache->get('total_price');
if (!$total_price) {
    $query = "SELECT SUM(price) AS total_price FROM products";
    $result = mysqli_query($conn, $query);
    $row = mysqli_fetch_assoc($result);
    $total_price = $row['total_price'];
    $memcache->set('total_price', $total_price, 0, 3600); // 缓存一小时
}

2. Optimize JSON data query
JSON (JavaScript Object Notation) is a lightweight data exchange format that is often used for storage and Transfer structured data. In the development of PHP and MySQL, frequent query operations on JSON data may cause performance degradation. The following are some methods to optimize JSON data query:

1. Using MySQL's JSON functions
   MySQL version 5.7 and above provides a series of JSON functions, such as JSON_EXTRACT, JSON_CONTAINS, etc., these functions can be directly Query and manipulate JSON data in the database. For example, to query JSON data containing specific key-value pairs, you can use the JSON_CONTAINS function:

$query = "SELECT * FROM products WHERE JSON_CONTAINS(details, '{"color": "red"}')";
$result = mysqli_query($conn, $query);

2. Use index
   If you need to query a certain field of JSON data, This field can be indexed to improve query efficiency. For example, to query a certain attribute in JSON data, you can use the JSON_EXTRACT function to query and index the field:

$query = "SELECT * FROM products WHERE JSON_EXTRACT(details, '$.color') = 'red'";
$result = mysqli_query($conn, $query);

3. Avoid nested JSON queries
   If JSON The structure of the data is deeply nested, and multi-layer nested queries may be generated during the query, which affects the query efficiency. In order to improve performance, you can try to avoid such nested structure queries, or use MySQL's JSON function to flatten the nested structure.

Summary:
Through the above method, you can effectively optimize the query operations of calculated fields and JSON data in PHP and MySQL. Using MySQL's built-in functions, calculated fields, indexes and other technologies, the calculation work can be transferred from PHP to the database, reducing the amount of data transmission and calculation, and improving query efficiency. At the same time, using caching technology to cache calculation results can further improve query performance. Finally, for querying JSON data, you can use MySQL's JSON functions and indexes to speed up query operations.

The above is the detailed content of How to optimize queries of PHP and MySQL calculated fields and JSON data through indexes?. For more information, please follow other related articles on the PHP Chinese website!