The number of visits to the company's website is increasing (average daily exceeding 100,000 PV), and MySQL has naturally become a bottleneck. Regarding the optimization of MySQL, the most basic thing is the optimization of the MySQL system parameters. MySQL has the greatest impact on the performance of the web architecture and is also a key core part. Let's take a look at some of the basics of MySQL optimization, including the optimization of MySQL itself (my.cnf).
MySQL has the greatest impact on the performance of the web architecture and is also a key core part. Whether MySQL settings are reasonably optimized directly affects the speed and load capacity of the web! At the same time, MySQL is also the most difficult part to optimize. It not only requires understanding some MySQL professional knowledge, but also requires long-term observation of statistics and judgment based on experience, and then setting reasonable parameters. Let's take a look at some of the basics of MySQL optimization, including the optimization of MySQL itself (my.cnf).
We introduce some parameters that have a greater impact on performance. Since the optimization settings of the my.cnf file are closely related to the server hardware configuration, we specify a common 2U server hardware environment: CPU: 2 Intel Xeon 2.4GHz Memory: 4GB DDR Hard disk: SCSI.
Below, we will explain based on the above hardware configuration combined with an optimized my.cnf:
[mysqld] port = 3306 serverid = 1 socket = /tmp/mysql.sock skip-locking #避免MySQL的外部锁定，减少出错几率增强稳定性。 skip-name-resolve #禁止MySQL对外部连接进行DNS解析，使用这一选项可以消除MySQL进行DNS解析的时间。但需要注意，如果开启该选项，则所有远程主机连接授权都要使用IP地址方式，否则MySQL将无法正常处理连接请求！ back_log = 384 #back_log参数的值指出在MySQL暂时停止响应新请求之前的短时间内多少个请求可以被存在堆栈中。 如果系统在一个短时间内有很多连接，则需要增大该参数的值，该参数值指定到来的TCP/IP连接的侦听队列的大小。不同的操作系统在这个队列大小上有它自己的限制。 试图设定back_log高于你的操作系统的限制将是无效的。默认值为50。对于Linux系统推荐设置为小于512的整数。 key_buffer_size = 256M #key_buffer_size指定用于索引的缓冲区大小，增加它可得到更好的索引处理性能。对于内存在4GB左右的服务器该参数可设置为256M或384M。注意：该参数值设置的过大反而会是服务器整体效率降低！ max_allowed_packet = 4M thread_stack = 256K table_cache = 128K sort_buffer_size = 6M #查询排序时所能使用的缓冲区大小。注意：该参数对应的分配内存是每连接独占，如果有100个连接，那么实际分配的总共排序缓冲区大小为100 × 6 ＝ 600MB。所以，对于内存在4GB左右的服务器推荐设置为6-8M。 read_buffer_size = 4M #读查询操作所能使用的缓冲区大小。和sort_buffer_size一样，该参数对应的分配内存也是每连接独享。 join_buffer_size = 8M #联合查询操作所能使用的缓冲区大小，和sort_buffer_size一样，该参数对应的分配内存也是每连接独享。 myisam_sort_buffer_size = 64M table_cache = 512 thread_cache_size = 64 query_cache_size = 64M #指定MySQL查询缓冲区的大小。可以通过在MySQL控制台观察，如果Qcache_lowmem_prunes的值非常大，则表明经常出现缓冲不够的情况；如果Qcache_hits的值非常大，则表明查询缓冲使用非常频繁，如果该值较小反而会影响效率，那么可以考虑不用查询缓冲；Qcache_free_blocks，如果该值非常大，则表明缓冲区中碎片很多。 tmp_table_size = 256M max_connections = 768 #指定MySQL允许的最大连接进程数。如果在访问论坛时经常出现Too Many Connections的错误提 示，则需要增大该参数值。 max_connect_errors = 10000000 wait_timeout = 10 #指定一个请求的最大连接时间，对于4GB左右内存的服务器可以设置为5-10。 thread_concurrency = 8 #该参数取值为服务器逻辑CPU数量*2，在本例中，服务器有2颗物理CPU，而每颗物理CPU又支持H.T超线程，所以实际取值为4*2=8 skip-networking #开启该选项可以彻底关闭MySQL的TCP/IP连接方式，如果WEB服务器是以远程连接的方式访问MySQL数据库服务器则不要开启该选项！否则将无法正常连接！ table_cache=1024 #物理内存越大,设置就越大.默认为2402,调到512-1024最佳 innodb_additional_mem_pool_size=4M #默认为2M innodb_flush_log_at_trx_commit=1 #设置为0就是等到innodb_log_buffer_size列队满后再统一储存,默认为1 innodb_log_buffer_size=2M #默认为1M innodb_thread_concurrency=8 #你的服务器CPU有几个就设置为几,建议用默认一般为8 key_buffer_size=256M #默认为218，调到128最佳 tmp_table_size=64M #默认为16M，调到64-256最挂 read_buffer_size=4M #默认为64K read_rnd_buffer_size=16M #默认为256K sort_buffer_size=32M #默认为256K thread_cache_size=120 #默认为60 query_cache_size=32M
Note:
1. If Key_reads is too large, you should Increase the Key_buffer_size in my.cnf and keep Key_reads/Key_read_requests at least 1/100. The smaller the better.
2. If Qcache_lowmem_prunes is very large, increase the value of Query_cache_size.
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