RE: Union all very slow.
- From: "Steiner, Randy" <Randy.Steiner@xxxxxxxx>
- To: "Dennis Williams" <oracledba.williams@xxxxxxxxx>
- Date: Wed, 25 Oct 2006 14:49:24 -0400
I am using 10g.
The difference in the execution plan is:
This is by itself:
INDEX* (RANGE SCAN) OF 'XP_DBCR_CARD_NO' (INDEX) (Co :Q1000
st=1 Card=3 Bytes=75)
and this is when it is part of the union ALL:
INDEX* (FAST FULL SCAN) OF 'XP_DBCR_CARD_NO' (IN :Q1000
DEX) (Cost=3251 Card=154734 Bytes=3868350)
> -----Original Message-----
> From: Dennis Williams [mailto:oracledba.williams@xxxxxxxxx]
> Sent: Wednesday, October 25, 2006 2:40 PM
> To: Steiner, Randy
> Cc: oracle-l@xxxxxxxxxxxxx
> Subject: Re: Union all very slow.
>
> Randy,
>
> I'd start by doing an EXPLAIN PLAN on each part and the whole thing.
You
> didn't mention your Oracle version, but maybe the CBO is getting smart
> enough to optimize the entire query, so is making a bad decision.
>
> Dennis Williams
>
>
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