RE: Union all very slow.

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_at_gmail.com]
> Sent: Wednesday, October 25, 2006 2:40 PM
> To: Steiner, Randy
> Cc: oracle-l_at_freelists.org
> 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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