select count(*)

From: Sarma Aryasomayajula <avnsarma_at_hotmail.com>
Date: Fri, 06 Oct 2006 11:10:16 -0400
Message-ID: <BAY109-F3389856BE090C7D6D749F3DA130@phx.gbl>

Hi!

I'm running the below query in PROD(10g R1) and ACPT(10g R2). the query returns in fraction of a second in PROD and, If I run the same query in ACPT, it's taking 30+ mins.

In Prod

S5UVAD@powls01 > set timin on
S5UVAD@powls01 > select count(*) from wlcbs_master.rpt_08_vew where 0=1;

COUNT(*)
----------
0

Elapsed: 00:00:00.07
S5UVAD@powls01 > sho user

In ACPT:

N7OTHA@AOWLS01 > set timin on
N7OTHA@AOWLS01 > select count(*) from rpt_08_vew where 0=1;

COUNT(*)
----------
0

Elapsed: 00:31:02.27

1. If I apply condition "where 0 = 1" on a single table, does oracle reads
entire table then applies this condition or otherwise since this is negative
condition does it apply without reading the entire table?

2. If the same condition is applied on a view which is join of 3 big
tables(paritioned)? How does oracle executes the query?

Can any one explain the above scenarious.

Regards,

Sarma

-- http://www.freelists.org/webpage/oracle-l Received on Fri Oct 06 2006 - 10:10:16 CDT