Re: Skip scans

Hi Mladen,

> part of ETL process

in a classical (periodic) ETL I have no good experience with indexes. I sometimes use a joke: "How can you distinguish between OLTP tuning expert and DW tuning expert?". The answer is: "If you have performance problems the OLTP guy decides to add an index, the DW man opt to remove one".

But I agree, nowadays "near real time ETL" gain some popularity, which is very close to OLTP, so the "old wisdoms" of classical ETL cease to be valid. May be, it is your case.

Anyway I would try to use fast full scan first or create a temporary table.

I guess there are also DBA's that would claim: "If you find that you need an index skip scan, that smells distinctly much as a bad design", but I don't belong to that school. I found skip scan particularly useful enhancement of index range scan e.g. in less known case of index skip scan on index with 3 columns say (a,b,c) where a is range constraint, b is free and c is equal constraint.

HTH Jaromir D.B. Nemec

http://www.db-nemec.com

• Original Message ----- From: "Mladen Gogala" <mgogala_at_allegientsystems.com> To: "'Oracle-L (E-mail)'" <oracle-l_at_freelists.org> Sent: Wednesday, December 29, 2004 7:47 PM Subject: Skip scans

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