mysql setting parameters

MySQL is a common relational database management system with rich functions and parameter configuration options. When using MySQL, adjusting appropriate parameter settings can improve database performance and stability. This article will discuss some important parameters in MySQL and provide guidance on how to set them.

1. Cache parameter setting

The cache involved in MySQL is divided into two types: query cache and buffer pool. The query cache allows MySQL to cache query results in memory, which can significantly reduce query time.

Turning on the query cache can be set by the following statement:

SET GLOBAL query_cache_size = [size];

where [size] is the cache size, usually between 16M and 512M, but it also depends on the total memory of the server. This parameter is disabled by default as this may cause performance degradation in high concurrency environments.

The buffer pool is an area in memory where MySQL caches data and index tables. MySQL uses the LRU (least recently used) algorithm to manage the buffer pool. The size of the buffer pool is best set to about 80% of the available memory, which can be set by the following statement:

SET GLOBAL innodb_buffer_pool_size = [size];

where [size] is the cache pool size, usually 2GB to 4GB, which may vary depending on the total size of the server. Varies depending on memory and application characteristics. By default, this parameter value is 128MB.

2. Connection parameter settings

The connection parameter configuration for MySQL includes the maximum number of connections, timeout time and maximum request data amount. Adjusting these parameters can make MySQL more stable under high load environments.

The maximum number of connections parameter specifies the maximum number of client connections that MySQL can handle simultaneously. If this limit is exceeded, new connections will be refused. The maximum number of connections can be set by the following statement:

SET GLOBAL max_connections = [number];

where [number] is the maximum number of connections allowed, usually between 100 and 1000. If this parameter is set too large, MySQL may excessively consume server resources in a high-concurrency environment. A value that is too low may cause the application to be unable to connect to the MySQL server. By default, this parameter is set to 151.

The timeout parameter specifies how long MySQL keeps the connection open. If the client does not send a request within the specified time, the MySQL server will close the connection. The timeout can be set by the following statement:

SET GLOBAL wait_timeout = [seconds];

where [seconds] is the connection waiting time, usually between 60 and 120 seconds. In some high-traffic applications, it may be necessary to increase this value. By default, this parameter is set to 8,640 seconds (i.e. 2.4 hours).

The maximum request data amount parameter specifies the maximum amount of data that MySQL allows the client to transmit in a single query. If the request exceeds this limit, the MySQL server will close the connection. The maximum amount of requested data can be set by the following statement:

SET GLOBAL max_allowed_packet = [size];

where [size] is the maximum request size, usually between 16M and 128M. If the application needs to transfer large files or BLOBs, it will need to be set to a higher value. By default, this parameter is set to 4MB.

3. Log parameter settings

MySQL supports several different log types, including slow query logs and binary logs. The slow query log records SQL queries that have potential performance issues, while the binary log records all change operations performed by the MySQL server. These logs will use disk space and affect MySQL performance. Therefore, the parameter settings for these logs are very important.

The slow query log parameter specifies which queries MySQL records are considered "slow queries", usually queries that take more than the specified time to execute. The slow query log can be set by the following statement:

SET GLOBAL slow_query_log = [value];
SET GLOBAL long_query_time = [seconds];

where [value] is to enable or disable the slow query log (1 means enable, 0 means disable). [seconds] is the execution time of the specified query before it is considered a slow query. It is recommended that the slow query log be turned off unless the application needs to analyze the queries in it.

The binary log parameter specifies how MySQL should log change operations. When binary logging is enabled, MySQL writes all change operations for backup and recovery purposes. The binary log can be set by the following statement:

SET GLOBAL log_bin = [value];

where [value] is to enable or disable the binary log (1 means enabled, 0 means disabled). This option can be enabled when the application needs to perform data recovery. It is recommended to enable binary logging only if required, as it consumes disk space and may impact performance.

Summary

MySQL is a powerful relational database whose performance and stability can be improved by adjusting appropriate parameter settings. This article discusses some common MySQL parameter settings, including cache parameters, connection parameters, and logging parameters. Please note that MySQL parameter settings need to be adjusted based on server configuration, application requirements, and environmental changes. Therefore, adjustments to these parameters require care and appropriate testing and monitoring to ensure their effectiveness.

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