Optimization strategies for data reading and query caching of PHP and MySQL indexes and their impact on performance

Optimization strategies for data reading and query caching of PHP and MySQL indexes and their impact on performance

Introduction:
In Web development, PHP and MySQL are two extremely important tools. PHP is a popular server-side scripting language used for developing dynamic websites and applications. MySQL is an open source relational database management system used to store and manage data. The combination of PHP and MySQL provides developers with powerful capabilities, but also faces some performance optimization challenges. This article will focus on the optimization strategies for data reading and query caching of PHP and MySQL indexes, as well as their impact on performance, and provide readers with specific code examples.

1. The Importance and Optimization Strategy of Index
The index is a data structure used to improve the query speed of the database. It quickly locates and retrieves records by creating specific references. In MySQL, you can create indexes on the columns of a table to speed up queries on specific columns.

1.1 Create appropriate indexes
Creating appropriate indexes is the key to improving query performance. First, make sure the index matches the columns being queried. If the index does not match the columns of the query, MySQL cannot use the index and must scan the entire table, causing performance degradation.

Sample code:

CREATE INDEX idx_name ON users (name);

1.2 Multi-column index
In a query statement with multiple columns forming conditions, you can create a multi-column index containing these columns to improve the query efficiency. efficiency.

Sample code:

CREATE INDEX idx_city_country ON users (city, country);

1.3 Avoid too many indexes
Although indexes can improve query performance, too many indexes can also cause performance degradation. Because every time data is inserted, updated, or deleted, the index needs to be updated. Therefore, you should avoid creating indexes on unnecessary columns.

2. Query cache optimization strategy and its impact on performance
Query cache is a caching technology provided by MySQL, which can cache the results of query statements in memory to avoid repeated execution of the same query statement. Query caching can significantly increase the speed of queries, but can also cause performance degradation in some cases.

2.1 Enable query cache
In order to use the query cache, first ensure that the query_cache_type parameter in the configuration file of the MySQL server is set to 1, indicating that the query cache is enabled.

Sample code:

query_cache_type = 1

2.2 Query cache hit rate
The query cache hit rate represents the proportion of query results successfully obtained from the cache. If the hit rate is low, it means that the query cache is not functioning adequately and needs to be optimized.

Sample code:

SHOW STATUS LIKE 'Qcache_hits';
SHOW STATUS LIKE 'Qcache_inserts';

2.3 Cache invalidation problem
The size of the query cache is limited. When the cache space is full, query results that are not frequently used recently will be replaced. Therefore, query caching is less effective for frequently updated data tables. This problem can be solved by not using the query cache for frequently updated data tables.

Sample code:

SELECT SQL_NO_CACHE * FROM users WHERE id = 1;

3. Best practices for performance optimization
In addition to index optimization and the use of query cache, there are other best practices for performance optimization, which can Further improve the performance of PHP and MySQL.

3.1 Using batch insert
When a large amount of data needs to be inserted, using batch insert can greatly improve performance. Batch inserts can be achieved by using the VALUES clause of the INSERT INTO statement.

Sample code:

INSERT INTO users (name, age) VALUES ('Tom', 20), ('Jerry', 25), ('Alice', 30);

3.2 Using prepared statements
Prepared statements can reduce the number of database executions, thereby improving performance. Use prepared statements to send query statements to the database server before executing parameter binding and querying.

Sample code:

$stmt = $mysqli->prepare("SELECT * FROM users WHERE age > ?");
$stmt->bind_param("i", $age);
$stmt->execute();

3.3 Reuse of database connections
Creating and closing database connections is a time-consuming operation, and repeated execution should be avoided as much as possible. You can optimize the reuse of database connections by using connection pooling technology.

Sample code:

$mysqli = new mysqli("localhost", "username", "password", "database");

Conclusion:
This article discusses the optimization strategy of data reading and query caching of PHP and MySQL indexes, and provides specific code examples. By properly creating indexes, enabling query caching, and following performance optimization best practices, you can significantly improve the performance of PHP and MySQL. Readers can perform performance optimization operations based on their own needs and actual conditions, combined with the optimization strategies provided in this article.

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