Re: Wow - has anyone used ROW_NUMBER() to get around using a UNION statement when UNION ALL doesn't work??
From: Greg Rahn <greg_at_structureddata.org>
Date: Mon, 8 Aug 2011 11:37:08 -0700
Message-ID: <CAGXkmiuWP=yrJ05u_M6dV-BKcNJ0jMdjv6xfGW9ohiG6FkNEpA_at_mail.gmail.com>
Mark -- the OP mentioned in the first email all 3 scenarions with some execution times and other comments. IMHO this makes it more than a logical discussion of theory. My point here is it's very difficult to comment on the "why" about something without knowing the technical bits of "what" it is doing. In this case, the "why" is about the performance, but the "what" required are the execution plans.
Date: Mon, 8 Aug 2011 11:37:08 -0700
Message-ID: <CAGXkmiuWP=yrJ05u_M6dV-BKcNJ0jMdjv6xfGW9ohiG6FkNEpA_at_mail.gmail.com>
Mark -- the OP mentioned in the first email all 3 scenarions with some execution times and other comments. IMHO this makes it more than a logical discussion of theory. My point here is it's very difficult to comment on the "why" about something without knowing the technical bits of "what" it is doing. In this case, the "why" is about the performance, but the "what" required are the execution plans.
On Mon, Aug 8, 2011 at 9:27 AM, Mark W. Farnham <mwf_at_rsiz.com> wrote:
> In the vast majority of cases I agree with Greg about posting plans.
> However, in this particular case the question is a purely logical
> consideration not based on any particular plans the optimizer is choosing.
> But a little bit more of context may be required.
-- Regards, Greg Rahn http://structureddata.org -- http://www.freelists.org/webpage/oracle-lReceived on Mon Aug 08 2011 - 13:37:08 CDT