Re: Yet Another COUNT(*)...WHERE...question

"Trevor Talbot" wrote:

>On 8/16/07, Rainer Bauer <usenet(at)munnin(dot)com> wrote:
>
>> My point is that whatever search criterias are involved and how many items are found eBay always returns the *accurate* number of items found.
>>
>> Before this drifts off:
>> * I do know *why* count(*) is slow using Postgres.
>> * I *think* that count(*) is fast on eBay because count is cheaper using Oracle (which eBay does: <http://www.sun.com/customers/index.xml?c=ebay.xml>).
>> * I realize that pagination for multi-million tuple results does not make sense.
>
>You got me curious, so I went hunting for more hints on what eBay
>actually does, and found these slides from a presentation given by two
>eBay engineers last year:
>http://www.addsimplicity.com/downloads/eBaySDForum2006-11-29.pdf

Quite interesting.

>It's, er, a whole different ballgame there. Database behavior is
>barely involved in their searching; they do joins and RI across
>database clusters within the _application_. I knew eBay was big, but
>wow...

Well then: forget the Oracle count(*) argument :-(

Rainer