发现 一个 查询状态为: Copying to tmp table 而且此查询速度非常慢,基本一分钟左右才出来,后面是很多查询,状态为lock。 此 分析 对我没有太大的作用,因此用 google 查询了一下,发现网上一篇文章讲得很好: Copying to tmp table on disk The temporary result set was larger than tmp_table_size and the t...
Copying to tmp table on disk 花费了大量的时间。 结果查找资料后 了解到 发现mysql可以通过变量tmp_table_size和max_heap_table_size来控制内存表大小上限,如果超过上限会将数据写到磁盘上,从而会有物理磁盘的读写操作,导致影响性能。 调整参数配置之后 就不会有这个问题了。 To set max_heap_table_size to 64...
Copying to tmp table on disk The temporary result set was larger than tmp_table_size and the thread is now changing the in memory-based temporary table to a disk based one to save memory. 哦,原来是这样的,如果查询超出了tmp_table_size的限制,那么mysql用/tmp保存查询结果,然后返回给客户端。 s...
这个可能跟你查询的SQL语句有关，有些语句比如distinct,order by之类的就需要copy到临时表之后再来进行处理。这个跟temp_table_size没有关系，如果是temp_table_size太小的话，那么出现的是copying to tmp table on disk 所以你应该检查下你的这个SQL语句看看能否优化，比如在需要排序的字段上添加索引 ...
这个可能跟你查询的SQL语句有关，有些语句比如distinct,order by之类的就需要copy到临时表之后再来进行处理。这个跟temp_table_size没有关系，如果是temp_table_size太小的话，那么出现的是copying to tmp table on disk 所以你应该检查下你的这 ...
Actually, I have found a fix to the problem. Albeit, I don't understand why it worked. I have mounted /tmp as tmpfs (for those unfamiliar with linux tmpfs is a sort of RAM disk). After that the server has been working over the weekend without any hickups....
系统显示类似如下结果:查询时间长、运行状态为 Sending data、Copyingto tmp table、Copyingto tmp table on disk、Sorting result、Using filesort 的查询会话可能均包含性能问题。若在QPS高导致CPU使用率高的场景中,查询执行时间通常... CopySnapshot-复制快照 ...
Copying to tmp table MySQL may use temporary tables during query execution. Ideally you would want to avoid this, since its an expensive and slow operation. It can be avoided by optimizing queries. Sometimes it can’t be completely avoided – in that case you want to make sure the temporary...
$ dd if=/floppy/floppy0 of=/tmp/output.file How to Copy a Disk (dd)Make sure that the source disk and destination disk have the same disk geometry. Become superuser or assume an equivalent role. Create the /reconfigure file so the system will recognize the destination disk to be added...
SHOW GLOBAL STATUS LIKE 'Created_tmp_disk_tables'; might help you monitor whether the change helps. The Profile is rather useless -- it lumps 99% of the interesting time into one bucket, such as > | Copying to tmp table | 14.084764 | without elaborating on whether that is MEMORY,...