MySQL implements data storage and compression technology

MySQL is an open source relational database management system that is widely used in many database management systems. With the rapid development of Internet applications, a large amount of data is generated. How to efficiently implement MySQL data storage and compression technology is Very necessary. This article will introduce MySQL's technology for data storage and compression.

1. MySQL data storage

MySQL data storage is completed through tables, and the data rows in the tables are stored in pages (Page), the default size of each page It is 16KB. Different storage engines will have different page sizes. For example, the InnoDB page size is 8KB. There are four MySQL storage engines, namely MyISAM, InnoDB, Memory and Merge, each with its own characteristics.

MyISAM is one of the most commonly used storage engines in MySQL. It provides fast query and insertion functions, but does not support transaction processing and row-level locks. Its storage method is a static row format, and data and indexes are stored separately. , the data and index of each table are stored in two files respectively, the .MYD file stores the data, and the .MYI file stores the index.

InnoDB is a transactional storage engine supported by MySQL. Compared with MyISAM, it provides higher data security and concurrent processing capabilities. In InnoDB, data and indexes are not separated and are stored in .ibd file.

The Memory storage engine provides fast data reading and writing capabilities. The data is stored in memory, but the data will disappear when MySQL is closed, so it is only used for development and testing. The Merge storage engine is not a real storage engine, but an engine that merges multiple MyISAM tables with the same structure into a logical table. When reading data, it will read the data from each table separately, and then merge it into one result and return it.

2. MySQL data compression

MySQL compression is accomplished by compressing tables or columns, and the compression method is related to the storage engine. The following introduces the compression methods of MyISAM and InnoDB storage engines.

1. MyISAM compression

MyISAM uses the Compressed Table method to compress data. Use the ALTER TABLE table_name ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=block_size command to convert the MyISAM table to Compressed table. Among them, block_size represents the size of the compressed block, which is generally set to 1024 or 2048. The compressed table stores pointers to the underlying data files. When the data is read, MySQL will decompress the data and return it to the client. Compressed tables have high compression ratios but may be slower to query.

2. InnoDB Compression

InnoDB uses page compression (Page Compression) method to compress data. Use the ALTER TABLE table_name ROW_FORMAT=COMPRESSED command to convert an InnoDB table to page compression. InnoDB page compression compresses data pages and indexes in the pages, which can greatly reduce storage space. However, it should be noted that InnoDB's page compression will lead to increased CPU usage, increased read overhead, and more I/O operations.

3. Optimize MySQL storage and compression

1. Reasonably select a storage engine

According to the required functions, data structure, and performance and security requirements, Choose the appropriate storage engine wisely.

2. Clear useless data in a timely manner

The storage space of MySQL is often limited by hardware resources, so it is necessary to clean up useless data in a timely manner to release storage space.

3. Compressed data

Compressed table and page compression can effectively reduce storage space usage, but it should be noted that the compression method will affect query performance and I/ The impact of O operations needs to be considered comprehensively.

4. Configure appropriate parameters

The default parameters of MySQL are not suitable for all scenarios. The parameters need to be changed according to the actual situation to achieve better performance optimization.

In short, MySQL's data storage and compression technology is a key part of achieving efficient database management. Reasonable selection of storage engines, timely cleaning of useless data, data compression, and reasonable configuration of parameters can help us optimize the performance and security of MySQL.

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