370: Physical Ordering of Data: Should You and Can You with ASSM?
Mark Farnham , Rightsizing, Inc. Biography
|Objectives:||Understand some of the theoretical underpinnings of why physical order of data can matter.
Be aware that sometimes physical ordering is cheap compared to value, sometimes expensive.
Have a method for thinking about whether physical ordering is worthwhile in a given case.
|Abstract:||Certain operations, some small like lookup lists, and some large, like some batch jobs (er, concurrent manager jobs) can perform better if the physical order of the data matches the predominant order of use. When is it worthwhile to attempt this ordering? How does ASSM (automatic segment space management) affect the ability to physically order data? Does ASSM have a material affect for good or ill on physical ordering? If so, when? The heart of the matter is that Oracle stores rows in blocks. When you run a query, what you want are the right rows. The fewer blocks you need to retrieve a read consistent image of in order to get the columns you want of the rows you want, the less it costs per row.|
|Date:||Wednesday, April 16, 2008|
|Time:||3:15 PM - 4:15 PM|