MySQL 核心参数优化

read_buffer_size 参数是如何影响写缓冲和写性能。
据说 read_buffer_size 参数只影响以下两种情况的写数据的性能：
SELECT INTO … OUTFILE ‘fileName‘
When writing to the OUTFILE, the writes are buffered before writing to OUTFILE
When filesort is used, during merge buffers and when merged results are written to a temporary file, then writes are buffered
下表是该文章测试的一些数据：
read_buffer_size physical writes exe time in secs
=0 (defaults to 8200) 23495 28.39
=131072 (default) 2937 27.44
=16777216 23 26.71
=33554432 12 26.00
=536870912 1 26.72
SELECT CONCAT('ALTER TABLE ',table_name,' ENGINE=InnoDB;') FROM information_schema.tables WHERE table_schema='db_name' AND `ENGINE`='myisam';