Re: Infromix & Data Warehousing Solutions

Doug Johnson wrote: > > Tim, > > Thanks for the info but we're not on the same page. I'm not talking about > the Informix query optimizer (access plan shown by 'explain plan'). There's > tons of info on www.informix.com on that optimizer. I'm talking about the > new MetaCube Warehouse Optimizer. My understanding is that it: > .. takes the 'audit' info from MetaCube about existing queries. > .. creates an analytical performance model (methodology unknown) > .. adds hypothetical aggregate tables to the 'schema' > .. re-evaluates the model to generate estimated query elapsed times. > Yes, and my point again is, Metacube is only as good as the data base it runs against. Think about what you've pointed out. Metacube can only optimize what is handed to it, to wit, your instructions about the data base schema your data base is made of. Metacube is a client interface, not a server piece. It can only hand off instructions to a server, namely XPS. I guess there are situations in the NT version of XPS where the server and the client co-exist, but in my little mind NT is no place for a data warehouse server, I don't care what anybody else says. If you fire off a Metacube query, it runs on the XPS system. If the Metacube query-generator builds an SQL statement that doesn't run right, because your system wasn't designed right, then yes, the optimizer on the XPS system DOES come into play. Metacube can have its own optimizer, but it ultimately must pass all queries through the front door of the data base engine. Once you see it in action you'll understand. > Dr. Chandra presented some nice plots that showed elapsed times decreasing > (and leveling off) and storage requirements increasing (and leveling off) as > N aggregates were added. She said that the next version would also recommend > some number of indexes with the same performance vs. storage trade-offs. > Given the difficulty of designing data warehouses and marts, this seems like > it could be an incredibly useful tool. I was just wondering if anyone has > used it. > > > The optimizer can only be as good > >as your best implementation of the data base. So all that stuff > >about fragmentation, disk layouts, and classic table design are really > >important. If not done right, no optimizer on either Metacube or XPS >will > do much good. -- Tim Schaefer tschaefe@mindspring.com tim_schaefer@fpl.com http://www.inxutil.com Informix on Linux? Dude... No Way! This Changes Everything