jackjoesh commented on issue #9616: URL: https://github.com/apache/shardingsphere/issues/9616#issuecomment-809874111
> For now the prepStmtCacheSize is 250. Much more time will be cost when the prepared statements count is over this size. The effect is significant. > > After I increase the prepStmtCacheSize, the qps of oltp_point_select is increased by 12% (from 77853 to 87284). > >  > > If a preparedStatement is in cache, execute an SQL will always send a **Request Close Statement**. > > If a preparedStatement is removed from the cache, The command **Request Close Statement** will be sent from the Proxy to MySQL server. And the following same SQL needs to be prepared again via command **Request Prepare Statement**. > > Both the **Request Close Statement** and the new **Request Prepare Statement** are additional cost compare with the single **Request Execute Statement** if increase the prepStmtCacheSize from 250 to 200000 , will it cost much memory? If a application has sharded to 20 dbs， is it dangerous? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
