MySQL数据库在什么时候开始失去性能?
物理数据库大小重要吗? 记录的数量重要吗? 性能下降是线性的还是指数级的?
我有一个我相信是一个大的数据库,大约有1500万条记录,占用了近2GB。基于这些数字,我是否有任何动机清理数据,或者我是否可以允许它继续扩展几年?
MySQL数据库在什么时候开始失去性能?
物理数据库大小重要吗? 记录的数量重要吗? 性能下降是线性的还是指数级的?
我有一个我相信是一个大的数据库,大约有1500万条记录,占用了近2GB。基于这些数字,我是否有任何动机清理数据,或者我是否可以允许它继续扩展几年?
当前回答
不,这并不重要。MySQL的速度大约是每秒700万行。所以你可以把它放大一点
其他回答
我将首先关注您的索引,然后让服务器管理员查看您的操作系统,如果所有这些都没有帮助,可能是时候进行主/从配置了。
这是真的。另一个通常有效的方法是减少重复处理的数据量。如果你有“旧数据”和“新数据”,并且99%的查询都使用新数据,只需将所有旧数据移动到另一个表中-并且不要查看它;)
->看看分区。
谈论“数据库性能”有点毫无意义,“查询性能”在这里是一个更好的术语。答案是:这取决于查询,它所操作的数据,索引,硬件等。您可以了解将要扫描多少行,以及使用EXPLAIN语法将使用哪些索引。
2GB并不算真正的“大”数据库——它更像是一个中等大小的数据库。
I once was called upon to look at a mysql that had "stopped working". I discovered that the DB files were residing on a Network Appliance filer mounted with NFS2 and with a maximum file size of 2GB. And sure enough, the table that had stopped accepting transactions was exactly 2GB on disk. But with regards to the performance curve I'm told that it was working like a champ right up until it didn't work at all! This experience always serves for me as a nice reminder that there're always dimensions above and below the one you naturally suspect.
还要注意复杂连接。除了交易量之外,交易复杂性也是一个很大的因素。
重构繁重的查询有时会大大提高性能。
The database size does matter. If you have more than one table with more than a million records, then performance starts indeed to degrade. The number of records does of course affect the performance: MySQL can be slow with large tables. If you hit one million records you will get performance problems if the indices are not set right (for example no indices for fields in "WHERE statements" or "ON conditions" in joins). If you hit 10 million records, you will start to get performance problems even if you have all your indices right. Hardware upgrades - adding more memory and more processor power, especially memory - often help to reduce the most severe problems by increasing the performance again, at least to a certain degree. For example 37 signals went from 32 GB RAM to 128GB of RAM for the Basecamp database server.