Re: UNION or UNION ALL - which faster

From: Antonio Sant <asant_at_iol.it>
Date: Sat, 25 Mar 2000 23:05:53 GMT
Message-ID: <lDbD4.14799$pn3.180553@news.infostrada.it>

my ha scritto nel messaggio ...
>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.
>

Well UNION ALL is faster (it doesn't delete duplicates). If the query is a FULL_TABLE_SCAN, you can use the hint PARALLEL to make it faster.

Bye! Received on Sat Mar 25 2000 - 17:05:53 CST