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Home -> Community -> Mailing Lists -> Oracle-L -> FW: What Happenned to this query (sloging)
Is this true? (see below).
Also, got this;
> It still holds true for Oracle 8. Oracle will not use an index on an IN
clause,
> but it will if you use EXISTS and there is a usable index on the columns
you're
> querying.
> - --
> Stephen Clouse <stephenc_at_theiqgroup.com>
> Senior Programmer, IQ Coordinator Project Lead
> The IQ Group, Inc. <http://www.theiqgroup.com/>
Wow! Is this correct???
-----Original Message-----
From: shildret_at_scotth.emsphone.com [mailto:shildret_at_scotth.emsphone.com]
On Behalf Of Scott T. Hildreth
Sent: Monday, January 29, 2001 11:51 AM
To: Simon Legdon
Cc: rnayathodan_at_yahoo.com; dbi-users_at_perl.org;
Jeffrey-Seger_at_forum-financial.com
Subject: RE: What Happenned to this query (sloging)
And Oracle 8, NOT EXISTS is huge speed increase.
On 29-Jan-01 Simon Legdon wrote:
> I was once told by an Oracle contractor that Oracle does not optimize NOT
IN
> queries well, and that the most efficient way of doing this is to use the
NOT
> EXISTS form that I suggested. This advice was for Oracle 7, I admit.
>
> I have used it and it does make a VERY noticable difference.
>
>>Actually, I'm not sure how Oracle or PG would handle this, but in
>>DB2, the nested loop join you warn against would depend on
>>how the optimizer is set up. It should set up temp tables and
>>do a hash join, which would be a lot quicker.
>
>
>
> ------------------------------------------------------------
> --== Sent via Deja.com ==--
> http://www.deja.com/
>
>
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