Re: Tuning Views

From: Pavel Polcar <pavel.polcar_at_berit.cz>
Date: 14 May 1998 07:56:21 GMT
Message-ID: <01bd7f0d$bcc34c60$47c3657e@polcar_nt4006>

Hi,
I think that you would observe the same behavior even with tables. If you select witout order by, Oracle fetches the first buffer of records and puts it
directly on output, etc. If you use order by, then all the record must be fetched
first, then ordered (in memory or using temporary segments) and only after that
can the first records be put on output. Regarding the views with unions, the reason may also be that you use UNION, not UNION ALL. UNION implies sorting to remove duplicates.

Regards,
--
Pavel Polcar

tlp_at_redrockgrp.com wrote in article <3559D051.1CC4_at_redrockgrp.com>...
> I'm looking for tips in tuning views...
>
> Specifically, I have a view that contains a union. When I do a
> simple 'select' from that view it responds promptly. If I try
> to attach an 'order by' clause it takes some time to respond.
>
> I have a feeling that I need to create a temporary table with a
> view on top of that in order to achieve the results I need BUT
> I figured I would request ideas from you folks first...
>
> Thanks for the input,
> Tracy (tlp_at_redrockgrp.com)
>
Received on Thu May 14 1998 - 02:56:21 CDT