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

On 8/16/07, Rainer Bauer <usenet@munnin.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

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...