BLOB write size and CPU

Someone asked to help in identifying a strange problem.  The problem found to be a combination of two issues, ASSM and the BLOB loading software, that manifested as an excessive CPU utilization. In this post we should see how different write buffer size can affect write efficiency. Read the rest of this entry »

Call-Less Cursor

Many people know that the Tkprof does not report base statistics and times for calls that have recursive calls. This can be handled by other alternative tools. There is one more unfortunate effect to watch out for when doing tuning of a DB that does fair amount of LOB operations. It seems to be more fundamental and much harder to cope with. Read the rest of this entry »

Tuning Collections in Queries [1]

[To Introduction

I will continue series about tuning collections in queries starting from the simplest case – collection of values joined to one table. Our subject SQL statements look similar to the following two forms. Read the rest of this entry »

Tuning Collections in Queries [Introduction]

[To Next Article [1]] [To Performance Study]

If you never heard of using collections instead of regular IN-LIST expressions, you might want to read varying elements in IN list article from AskTom. It unfortunately has little information about the way CBO treats collections. So, if you have problems with tuning queries that employ nested tables or just evaluating what is in the way please read on. Read the rest of this entry »