Обсуждение: Postgres performance issue

Hi Everyone,

I am running Postgres 7.1 and php 4.0.
I have a question:  Why does postmaster use 80% of the CPU on a simple sql
query?  I have a form that displays a list of customers based on a criteria
they enter.  If the user doesn't enter in a criteria it will display all the
customer in the database.  Basically the sql stmt is

select * from customer where upper(name) like  upper('$criteria%')

Does anyone know what the limitation on Postgres? Like how many records
before it starts to seize and choke on the performance side?


Thanks

Linh

>select * from customer where upper(name) like  upper('$criteria%')
>
>Does anyone know what the limitation on Postgres? Like how many records
>before it starts to seize and choke on the performance side?

I don't think it's choking on the server side.  How many records would you
expect to get back if you select ALL records?  If there are a lot of them,
you may be running out of memory on your client (PHP in this case) or it's
allocating space for each record as it comes in which may be what's causing
your performance hit.  Also, if you can determine that ALL records are being
requested, it would be faster to remove the LIKE clause since this requires
the server to examine each record whereas just a SELECT * from customer
doesn't.

len morgan