mysql内存计算公式（转）

mysql used mem = key_buffer_size + query_cache_size + tmp_table_size

　　+ innodb_buffer_pool_size + innodb_additional_mem_pool_size + innodb_log_buffer_size

　　+ max_connections * ( read_buffer_size + read_rnd_buffer_size + sort_buffer_size

　　+ join_buffer_size + binlog_cache_size + thread_stack)

在mysql 中输入如下命令，可显示各占内存参数大小

SHOW VARIABLES LIKE   'key_buffer_size';
SHOW VARIABLES LIKE   'query_cache_size';
SHOW VARIABLES LIKE   'tmp_table_size';
SHOW VARIABLES LIKE   'innodb_buffer_pool_size';
SHOW VARIABLES LIKE   'innodb_additional_mem_pool_size';
SHOW VARIABLES LIKE   'innodb_log_buffer_size';
SHOW VARIABLES LIKE   'read_buffer_size';
SHOW VARIABLES LIKE   'read_rnd_buffer_size';
SHOW VARIABLES LIKE   'sort_buffer_size';
SHOW VARIABLES LIKE   'join_buffer_size';
SHOW VARIABLES LIKE   'binlog_cache_size';
SHOW VARIABLES LIKE   'thread_stack';

在mysql 中输入如下命令，可自动计算自己的当前配置最大的内存消耗

SHOW VARIABLES LIKE'innodb_buffer_pool_size';
SHOW VARIABLES LIKE 'innodb_additional_mem_pool_size';
SHOW VARIABLES LIKE 'innodb_log_buffer_size';
SHOW VARIABLES LIKE 'thread_stack';
SET @kilo_bytes = 1024;
SET @mega_bytes = @kilo_bytes * 1024;
SET @giga_bytes = @mega_bytes * 1024;
SET @innodb_buffer_pool_size = 2 * @giga_bytes;
SET @innodb_additional_mem_pool_size = 16 * @mega_bytes;
SET @innodb_log_buffer_size = 8 * @mega_bytes;
SET @thread_stack = 192 * @kilo_bytes;
SELECT
( @@key_buffer_size + @@query_cache_size + @@tmp_table_size
+ @innodb_buffer_pool_size + @innodb_additional_mem_pool_size
+ @innodb_log_buffer_size
+ @@max_connections * (
@@read_buffer_size + @@read_rnd_buffer_size + @@sort_buffer_size
+ @@join_buffer_size + @@binlog_cache_size + @thread_stack
) ) / @giga_bytes AS MAX_MEMORY_GB;