The optimisation paths available.
The number of blocks involved
The method used to read the blocks
The amount of block cleanout that takes place on the read
The amount of concurrent activity on the disks at the same time
--
Jonathan Lewis
http://www.jlcomp.demon.co.uk
Host to The Co-Operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html
Author of:
Practical Oracle 8i: Building Efficient Databases
Morten Primdahl wrote in message <3CB14F73.4000106_at_caput.com>...
>
>Hi. What affects the execution speed of count(*):
>
>SQL> select count(*) from table_a;
>
> COUNT(*)
>----------
> 382784
>
>Elapsed: 00:00:00.28
>SQL> select count(*) from table_b;
>
> COUNT(*)
>----------
> 382648
>
>Elapsed: 00:00:05.40
>
>The tables have a similar amount of rows, yet the count
>on table_b is noticably slower than the count on table_a.
>
>--
>Morten Primdahl Caput A/S Phone +45 70 12 24 42
>System Integrator Nygade 6 Fax +45 70 11 24 42
>morten@caput.com DK-1164 Kbh K http://www.caput.com/
>
Received on Mon Apr 08 2002 - 03:23:24 CDT
