最佳做法是启动MySQL,连接所有会话,然后继续关注顶级会话的VIRT列,mysqld行的数目通常保持相对稳定,这就是实际的内存总用量,减去所有的静态MySQL内存区域,就得到了实际的所有会话内存,然后除以会话的数量就得到平均值。 1、read_buffer_size 缓存连续扫描的块,这个缓存是跨存储引擎的,不只是MyISAM表。 2、sort_buffer...
在MySQL,排序主要有两种方式: Using filesort :通过表索引或全表扫描,读取满足条件的数据行,然后在排序缓冲区sort buffer中完成排序操作,所有不是通过索引直接返回排序结果的排序都叫 FileSort 排序; Using index :通过有序的索引顺序扫描直接返回有序数据,这种情况即为 using index,不需要额外排序,操作效率高。 对...
SET @@GLOBAL.sort_buffer_size = 50000, sort_buffer_size = 1000000;System Variable References in Expressions To refer to the value of a system variable in expressions, use one of the @@-modifiers (except @@PERSIST. and @@PERSIST_ONLY., which are not permitted in expressions). For exampl...
Bug #88071 An arresting Performance degradation when set sort_buffer_size=32M Submitted: 12 Oct 2017 8:17Modified: 22 Dec 2017 12:55 Reporter: ashe sun (OCA) Email Updates: Status: No Feedback Impact on me: None Category: MySQL ServerSeverity: S3 (Non-critical) Version: 5.7.19OS: ...
SET@@GLOBAL.sort_buffer_size=50000,sort_buffer_size=1000000; System Variable References in Expressions To refer to the value of a system variable in expressions, use one of the@@-modifiers. For example, you can retrieve system variable values in aSELECTstatement like this: ...
确定MySQL的每个连接使用的内存 sort_buffer_size join_buffer_size read_buffer_size read_rnd_buffer_size 确定需要为操作系统保留多少内存 如何为缓存池分配内存 Innodb_buffer_pool_size 总内存-(每个线程锁需要的内存*连接数)- 系统的保留内存 key_buffer_size ...
Status:ClosedImpact on me: None Category:MySQL Server: DocumentationSeverity:S3 (Non-critical) Version:5.1OS:Any Assigned to:Paul DuBoisCPU Architecture:Any [8 Jan 2009 10:21] Horst Hunger Description:Values set for "sort_buffer_size" are rounded to other values, which is not described in th...
MYSQL影响性能的主要参数 公共参数 max_connections = 151 #同时处理最大连接数,推荐设置最大连接数是上限连接数的80%左右 sort_buffer_size = 2M #查询排序时缓冲区大小,只对order...1024 #打开文件数限制,如果show global status like 'open_files'查看的值等于或者大于open_files_limit值时,程序会无法连接数...
# sort_buffer_size = 2M # read_rnd_buffer_size = 2M datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 log-error=/var/log/mysqld.log ...
This threadhttp://forums.mysql.com/read.php?21,86150,86150#msg-86150 seems to indicate that you can set myisam_max_sort_file_size and myisam_max_extra_sort_file_size to a value higher than available memory (but lower than available tmp disk) to force the DB to do a “repair by so...