Hello, it looks to me like the 1st query did not hit the data cache, and was punished with lots of data I/O. All following queries possibly then feed from the cache to a certain extend and need not to access the hard disk too often.
As dropping, loading, and backup already takes some time, and is done before the server is 'switched on' for the application, possibly executing the nasty query before from some client program (e.g. dbmcli) may just feed the cache, so that the 1st query from the application isn't really the 1st one ... Alexander Schröder SAP DB, SAP Labs Berlin > -----Original Message----- > From: Albert Steckenborn [mailto:[EMAIL PROTECTED] > Sent: Monday, December 15, 2003 4:47 PM > To: [EMAIL PROTECTED] > Subject: Tuning Question tables (5GB) with complete reload each day > > > Hi folks, > > of course somebody could give me a hint for my questions. > > We are running some applications with tables up to 5GB with > SAPDB 7.4 on > Linux. > Each day we are getting the whole data again in partial steps > (with size > from 0,1 GB to 1,5 GB) at different times. > > At the Moment we are dropping the whole table and indexes for 4 times > per day and creating everything new, loading new data with > fastload to > our Standby Database-Server. At this Database-Server we are doing > everything else to do (creating indexes a.s.o.). Then we are > running a > backup of the Database switching the applications to this Server and > running a recover of our backup at the Main Database-Server. > After this we are switching back to the Main Server. > > Now our Problem: > The first selects (over 1.500.000 rows) after this needs up to 30 > seconds for getting the results. Thats definitiv to much. No way for > optimising indexes (we have done our best. Explain looks > nice). With the > second select, the result is coming up directly (0 sec. in reason of > caching). > > Now the Question: > Do you think it is making a scence for performance issues to > drop only > the data (and reload the new) and not the whole table with indexes. > > Of course you have an other idea what we can do. > > With best rgds. > > Albert > > > -- > MaxDB Discussion Mailing List > For list archives: http://lists.mysql.com/maxdb > To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] -- MaxDB Discussion Mailing List For list archives: http://lists.mysql.com/maxdb To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
