Обсуждение: Counting all results before LIMIT

We have a PHP web application that pulls results from the database and paginates them.

You cant. There is an article about count performance. Generally its slow but latest version 9.2 i think supports index for count under some condition.But 300 isnt that much that you should worry.Another modern solution is to not count results just add one more at limit to see if there is next page.

You could use a windowing function.  Something like:

You could use a windowing function.  Something like:

SELECT x, y, z, COUNT(*) OVER()

FROM Foo

LIMIT 50;

Good to know! I'll give a try!

On Fri, Oct 5, 2012 at 8:02 AM, P Gouv <kadmos@gmail.com> wrote:

You cant. There is an article about count performance. Generally its slow but latest version 9.2 i think supports index for count under some condition.But 300 isnt that much that you should worry.Another modern solution is to not count results just add one more at limit to see if there is next page.

I've used two queries for >100 000 (with filters applied - table has > 1 800 000 records), and is very acceptable (<200ms with 8Gb and Xeon dual core).

Edson.

On Fri, Oct 5, 2012 at 5:29 PM, Moshe Jacobson <moshe@neadwerx.com> wrote:

We have a PHP web application that pulls results from the database and paginates them.

We show e.g. "1-50 of 300" so the user knows how many total results there are, and which ones are currently being displayed.

To achieve this, we use a query with LIMIT...OFFSET to get the displayed results, and we do another identical query using count(*) to get the total count.

Is there a more efficient way to do this that does not require us to do two queries? I just feel that it's a waste of resources the way we do it.

Thanks!

--

Moshe Jacobson
Nead Werx, Inc. | Senior Systems Engineer

2323 Cumberland Parkway, Suite 201 | Atlanta, GA 30339
moshe@neadwerx.com | www.neadwerx.com