RE: Difference between count(1) and count(*)
- From: "Peter Miller" <Peter.Miller@xxxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 8 Jul 2004 14:40:17 +0100
1,749,951 rows returned in every case
count(rowid) - approx 3.2 secs
count(obj#) - approx 3.5 secs
count(1) - approx 3.6 secs
count(*) - approx 3.6 secs
count(rownum)- approx 4.6 secs
count(source)- approx 8.6 secs
-----Original Message-----
From: Srinivasan Vasan [mailto:Vasan.Srinivasan@xxxxxxxxxxxxx]
Sent: 08 July 2004 12:47
To: 'oracle-l@xxxxxxxxxxxxx'
Subject: RE: Difference between count(1) and count(*)
Try the following test (using your own table instead of sys.source$ if =
you
wish) on your setup and forever dispel any myths: :-)
=20
set trimspool on
set timing on
spool test_count.lst
Prompt Using Sys.Source$ for the test
Prompt
Prompt Row Count using all columns
select count(*) from sys.source$;
Prompt Row Count using a specific numbered column
select count(1) from sys.source$;
Prompt Row Count using the pseudo-column rownum
select max(rownum) from sys.source$;
Prompt Row Count using the ROWID column
select count(rowid) from sys.source$;
Prompt Counting a Not-NULL column
select count(obj#) from sys.source$;
Prompt Counting a NULL column
select count(source) from sys.source$;
spool off
set timing off
set trimspool off
=20
Cheers,=20
=20
Vasan.
-----Original Message-----
From: Jared Still [mailto:jkstill@xxxxxxxxxx]=20
Sent: 08 July 2004 08:20
To: Oracle-L Freelists
Subject: Re: Difference between count(1) and count(*)
=20
On Wed, 2004-07-07 at 23:28, Lyndon Tiu wrote:
> On Thu, 8 Jul 2004 11:27:28 +0530 oracle-l@xxxxxxxxxxxxx wrote:
> > Dear All,
> > Can you let me know the difference between count(*) and count(1) ?
>=20
> count(1) is supposed to be more efficient and faster.
=20
Notice the qualifier: 'supposed to be'
=20
Was the claim backed up by evidence?
=20
Jared
=20
=20
=20
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