How does the read-write ratio of PHP and MySQL indexes and query types affect query performance?

The read-write ratio of PHP and MySQL indexes and the impact of query types on query performance

Introduction:
When developing web applications, PHP and MySQL They are two commonly used technology stacks. Among them, MySQL, as a relational database, is an important data storage and query tool for applications. In order to improve query performance, it is very important to use indexes appropriately. This article will explore the impact of the read-write ratio and query type on query performance in PHP and MySQL indexes, and provide relevant code examples.

1. The concept and function of index
The index is a special data structure in the database, used to speed up data retrieval. It is similar to a dictionary directory and can quickly locate the corresponding record based on the value of a certain field. In MySQL, indexes can be defined on one or more columns, which can speed up queries, but will also take up a certain amount of storage space.

2. The impact of index read-write ratio on performance

1. Read operation
   When the number of records in the data table is large, but the read operations far exceed the write operations , Reasonable index design can significantly improve the speed of reading data. For example, for fields that require frequent query operations, you can add indexes to quickly locate records that meet the conditions. However, it should be noted that too many indexes will also lead to a decrease in query performance, so the quantity and quality of indexes need to be weighed.

The following is a simple example of optimizing the index based on the read-write ratio.

Code example:

// 利用索引进行查询
$query = "SELECT * FROM users WHERE username = 'test_user'";
$result = $mysqli->query($query);

// 不使用索引进行查询
$query = "SELECT * FROM users";
$result = $mysqli->query($query);

In the above example, if read operations are very frequent, we can add an index to the username field to quickly locate records that meet the conditions. .

2. Write operation
   When writing data, the existence of the index will have a certain impact on the performance of insertion and update. Every time a write operation is performed, the database needs to maintain corresponding indexes, so the number and quality of indexes will also have a certain impact on write performance. Therefore, when adding indexes, you need to weigh the proportion of read and write operations to avoid excessive indexes causing a decrease in write performance.

The following is a simple example of optimizing the index based on the read-write ratio.

Code example:

// 插入数据
$query = "INSERT INTO users (username, password) VALUES ('test_user', 'password')";
$result = $mysqli->query($query);

// 读取数据
$query = "SELECT * FROM users WHERE username = 'test_user'";
$result = $mysqli->query($query);

In the above example, if write operations are very frequent, we can consider not adding an index to reduce the overhead of maintaining the index when writing.

3. The impact of query types on performance
Different query types have different impacts on performance. Common query operations will be explained below.

1. Precise query
   Precise query refers to obtaining records that meet the conditions through one or more conditions. Such queries are usually simple, and indexes can be used to speed up the query. For example, to query user information by user name, you can use the WHERE statement and add the corresponding index.

Code example:

$query = "SELECT * FROM users WHERE username = 'test_user'";
$result = $mysqli->query($query);

2. Fuzzy query
   Fuzzy query refers to obtaining records that meet the conditions through a fuzzy condition. Such queries typically cannot use indexes to speed up the query because indexes are built based on exact values. If you need to perform fuzzy queries, you can consider using full-text indexes or other search engines to improve query performance.

Code example:

$query = "SELECT * FROM users WHERE username LIKE '%test%'";
$result = $mysqli->query($query);

3. Aggregation query
   Aggregation query refers to a query operation that performs statistics and calculations on a set of records, such as summing and averaging. wait. Such queries usually require processing of multiple records, so the use of indexes will be limited. You can consider adding indexes to aggregate fields to improve query performance.

Code example:

$query = "SELECT SUM(sales) FROM products GROUP BY category";
$result = $mysqli->query($query);

Conclusion:
The read-write ratio and query type of PHP and MySQL indexes have an important impact on query performance. Through reasonable index design, the query speed can be improved. In practical applications, the quantity and quality of indexes need to be weighed based on specific scenarios and needs. When the ratio of reads and writes is high, you can consider adding appropriate indexes to improve query performance; when write operations are frequent, you can consider reducing the number of indexes to reduce the cost of maintaining indexes. In addition, different types of query operations have different impacts on performance, and queries need to be optimized according to specific conditions. In short, reasonable use of indexes and combined with specific business scenarios can improve the performance and user experience of web applications.

References:

1. MySQL official documentation: https://dev.mysql.com/doc/indexes.html
2. PHP official documentation: https:/ /www.php.net/manual/zh/book.mysqli.php
3. Wang Weigen, Cao Xiangguo. Large-scale website technical architecture. Machinery Industry Press, 2013.

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