On 2001-07-07 18:16:26 -0500, Steven Lembark wrote:
> - Steve Howard <[EMAIL PROTECTED]> on 07/07/01 17:54:18 -0500:
>
> > do a
> > SELECT COUNT(*) FROM <tablename> WHERE ...
> >
> > A count is almost always faster than actually returning that row, and
> > requires even less network bandwidth to return the result. Of course, it a
> > result of 1 is returned - the row exists.
>
> Don't try this in Oracle, it immediately degenerates into a
> table scan.
It shouldn't, and AFAICS it doesnt:
SELECT STATEMENT
SORT AGGREGATE
INDEX UNIQUE SCAN ITBOSSTEST.TRL_PK
is the result of an explain plan for
select count(*) from translations where trl_id=100
The unique scan looks good, although I don't understand why oracle wants
to sort a single row :-)
We are using the rule-based optimizer on this database though, since the
cost-based optimizer sometimes acts very strangely (we had a query which
took almost 4 hours with the CBO (two nested full table scans on the
translations table), and less than 0.01 seconds with the RBO).
hp
--
_ | Peter J. Holzer | It's nice to fix problems by accident.
|_|_) | Sysadmin WSR / LUGA | -- Theo de Raadt
| | | [EMAIL PROTECTED] | <[EMAIL PROTECTED]>
__/ | http://www.hjp.at/ | on bugtraq 2001-03-19
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