MERGE tables are a clever way to get around operating-system restrictions on maximum file sizes. Because each MyISAM table is stored in a single file, tables are limited in size by the maximum file size of the operating system. We get around this by creating a MERGE table, a construct that allows you to treat multiple MyISAM tables as a single table for the purpose of queries.这个可能对你有用 就是说myisam的表的大小和操作系统有关
| net_buffer_length | 16384 |
| net_read_timeout | 30 |
| net_retry_count | 10 |
| net_write_timeout | 60
net_write_timeout:
Number of seconds to wait for a block to be written to a connection before aborting the write.