From: gogala.mladen@gmail.com   
      
   The time has come when Oracle application tuning is quickly becoming too   
   complex to do efficiently. There is the basic optimizer, dynamic   
   sampling, then +ACI-adaptive mayhem+ACI as J. Lewis has succintly put it,   
   parallel execution and pifalls with direct read vs. buffered read. To add   
   insult to injury, there is a whole lot issues with latches and mutexes,   
   NUMA architecture and a whole set of new options like in-memory option   
   and advanced compression options.   
   Of course, since all of that is not complex enough, the database can now   
   run +ACI-in the cloud+ACI, so IO times and CPU times may not be what they seem.   
   There is not much difference between random access IO and sequential IO   
   in the cloud, because VMDK disks are essentially files, which may be   
   fragmented. The result will be turning many of a sequential scans   
   (scattered reads, as Oracle calls them) into random access IO, which is,   
   of course, significantly slower than sequential access, when more than a   
   single block is being read.   
   I am wondering whether it's time to take the +ACI-black box approach+ACI and   
   use   
   just the automatic tuning tools. The whole thing is overwhelming and to   
   master it takes years. And when you do, it all goes invalid with the new,   
   even more complex version.   
   At the same time, the relevant information is getting more and more scant   
   and hard to find. Oracle is getting more and more closed every day.   
      
      
      
   --   
   Mladen Gogala   
   The Oracle Whisperer   
   http://mgogala.byethost5.com   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)