Re: Skip scans
- From: "jaromir nemec" <jaromir@xxxxxxxxxxxx>
- To: <mgogala@xxxxxxxxxxxxxxxxxxxx>, "'Oracle-L (E-mail)'" <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 29 Dec 2004 23:03:36 +0100
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@xxxxxxxxxxxxxxxxxxxx>
To: "'Oracle-L (E-mail)'" <oracle-l@xxxxxxxxxxxxx>
Sent: Wednesday, December 29, 2004 7:47 PM
Subject: Skip scans
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