How to use in-memory tables and cache tables in MySQL to improve query speed?

How to use memory tables and cache tables in MySQL to improve query speed?

MySQL is a commonly used relational database management system. Its high performance and reliability make it the first choice for many developers. Query speed is a very important issue when dealing with large amounts of data. In order to improve query speed, MySQL provides two special table types: memory tables and cache tables. This article will introduce how to use these two table types to optimize query performance and give corresponding code examples.

1. Memory table

The memory table is a table that is completely stored in the memory. It does not occupy hard disk space and the query speed is very fast. Before using the memory table, you need to ensure that the system has enough memory available.

The syntax for creating a memory table is as follows:

CREATE TABLE tablename
(

column1 datatype,
column2 datatype,
...

)
ENGINE=MEMORY;

The following is a Simple example, create a memory table to store student information:

CREATE TABLE students
(

id INT,
name VARCHAR(255),
age INT

)
ENGINE=MEMORY;

Insert data into memory The syntax of the table is as follows:

INSERT INTO tablename (column1, column2, ...)
VALUES (value1, value2, ...);

The following is an example to insert two student information into the memory table:

INSERT INTO students (id, name, age)
VALUES (1, 'Alice', 20),

   (2, 'Bob', 21);

Syntax for querying the memory table Same as a normal table:

SELECT * FROM tablename
WHERE condition;

The following is an example to query the information of students older than 20 in the memory table:

SELECT * FROM students
WHERE age > 20;

2. Cache table

The cache table is a special table type that uses the query caching function of MySQL. When a query is cached and the same query is executed, MySQL will directly return the cached results without executing the query again, thus improving query speed.

Before using the cache table, you need to ensure that MySQL's query cache function is enabled. The query cache can be checked and set through the following two system variables:

SHOW VARIABLES LIKE 'query_cache_type'; -- Check the query cache type

SET GLOBAL query_cache_type = ON; -- Enable query cache

The syntax for creating a cache table is as follows:

CREATE TABLE tablename
(

column1 datatype,
column2 datatype,
...

)
ENGINE=MEMORY;

The following is one Simple example, create a cache table to store student information:

CREATE TABLE students
(

id INT,
name VARCHAR(255),
age INT

)
ENGINE=MEMORY;

Insert data into cache The syntax of the table is the same as that of the memory table:

INSERT INTO tablename (column1, column2, ...)
VALUES (value1, value2, ...);

Query the cache table The syntax is the same as the memory table:

SELECT * FROM tablename
WHERE condition;

The following is an example to query the information of students older than 20 in the cache table:

SELECT * FROM students
WHERE age > 20;

It should be noted that MySQL's query caching function has certain shortcomings. When the data in the table changes (insert, update, delete operations), the cache will be cleared and the next query will be re-executed. Therefore, when using cache tables, you need to carefully consider the changes in data.

Summary:

Query speed can be improved in MySQL by using memory tables and cache tables. The memory table can be stored in the memory, avoiding the IO operation of the hard disk, and the query speed is very fast. The cache table uses MySQL's query caching function to directly return cached results and reduce query execution time. However, it should be noted that the memory table needs to have enough memory available, and the cache table needs to consider cache clearing when the data changes.

I hope this article will help you understand how to use memory tables and cache tables in MySQL to improve query speed.

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