Re: select count(*) very slow on an already vacuumed table.

On Thursday 15 April 2004 08:10, Rajesh Kumar Mallah wrote:
> The problem is that i want to know if i need a Hardware upgrade
> at the moment.
>
> Eg i have another table rfis which contains ~ .6 million records.

> SELECT count(*) from rfis where sender_uid > 0;

> Time: 117560.635 ms
>
> Which is approximate 4804 records per second. Is it an acceptable
> performance on the hardware below:
>
> RAM: 2 GB
> DISKS: ultra160 , 10 K , 18 GB
> Processor: 2* 2.0 Ghz Xeon

Hmm - doesn't seem good, does it? If you run it again, is it much faster
(since the data should be cached then)? What does "vmstat 10" show while
you're running the query?

One thing you should have done is read the performance tuning guide at:
http://www.varlena.com/varlena/GeneralBits/Tidbits/index.php
The default values are very conservative, and you will need to change them.

> What kind of upgrades shoud be put on the server for it to become
> reasonable fast.

If you've only got one disk, then a second disk for OS/logging. Difficult to
say more without knowing numbers of users/activity etc.

--
Richard Huxton
Archonet Ltd