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Re: UNION or UNION ALL - which faster

From: Patrick Hamou <patrick_hamou_at_hotmail.com>
Date: Sat, 25 Mar 2000 22:51:04 GMT
Message-ID: <spbD4.17204$1C2.464672@news20.bellglobal.com>


The union all is faster than the union because it doesn't have to check for duplicates...

Depending on your needs, if you don't care about the duplicates or if your data-architecture prevents duplicates from the start, then I recommend you to use the UNION-ALL operator.

Patrick Hamou
Oracle Certified DBA
patrickh_at_sympatico.ca

my <mohamed.yusuf_at_sympatico.ca> wrote in message news:Cj3D4.8701$n03.403288_at_news20.bellglobal.com...
> hi everybody,
>
> I'm hitting 5 tables with millions of records using operator UNION or
UNION
> ALL. both takes hrs to get the result - I'm not worried since UNION ALL
> returns dublicates as well. Can anybody tell me the best way or
alternative
> ways that makes faster.
>
>
Received on Sat Mar 25 2000 - 16:51:04 CST

Original text of this message

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