等了半响mysql client 内存撑爆了。原因是mysql默许将一切数据都查询好后一次回来给客户端。
摘自Mysql command-line tool文档：
If you have problems due to insufficient memory for large result sets, use the quick option. This forces mysql to retrieve results from the server a row at a time rather than retrieving the entire result set and buffering it in memory before displaying it. This is done by returning the result set using the mysql_use_result() C API function in the client/server library rather than mysql_store_result().
Do not cache each query result, print each row as it is received. This may slow down the server if the output is suspended. With this option, mysql does not use the history file.