Morten Torstensen wrote: > John R Pierce wrote: >> in our case, our production systems are a very large very complex >> realtime oracle database running on large scale Sun enterprise >> hardware on bigiron EMC storage, using dozens and dozens of raid10 >> logical volumes as you do NOT want to have a single 10TB volume, >> sorry. by hand optimizing the tablespace layouts of the applications >> tables and indicies, which have very specific access patterns, we can >> get double the throughput of the blind 'just stripe the universe' >> approach. Since > > Oh you would not have a single 10TB volume of course: and it is still a > little quaint to hand optimize tablespaces. That is something we did in > the 90s. Our own tests on multi-TB databases and modern SAN systems, > the shotgun approach beat hand optimization every time. And we are > talking about people with dozens of years with SQL optimization behind > them. Intelligent I/O prefetch adaption, intelligent and dynamic access > plans... the world of performance in the RDBM world is changing and old > rules for performance are changing with it. > Im not sure im following the language correctly ... Morten and John - you seem to be at opposite ends of the opinion scale about hand optimising tablespaces? Maybe you have different definitions of "hand optimising tablespaces"? Morten - Are your systems similar enough to Johns to make a valid comparison about the merits of the shotgun approach vs "hand optimising tablespaces"? For the benefit of the rest-of-us DBAs, i understand "hand optimising tablespaces" to mean ... "choosing where a table (or a partition of a table) will physically live, and where its indexes will live so that roughly; sum(reads/s + writes/s on spindle [1..n])^2 ) is as low as possible. (ie balanced across all spindles). I have never had a db span anything bigger than a redundant fibre channel array controller (yep - a bit outdated now), but if it did, then balance across n controllers as well. I imagine you also decide if/which tables or indexes are pinned in memory? Thanks to both of you for the info so far :) Regards, MrKiwi