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From:Jigal van Hemert Date:July 9 2004 2:07pm
Subject:Re: Cost of joins?
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From: "Jochem van Dieten" <jochemd@stripped>
> > After adding a column for "one level up", adding indexes, optimizing the
> > query it took only a few hundreds of seconds.
>
> Maybe I misunderstand the problem, but I get the impression you have
> the category computers>internet>providers>adsl and you want to count
> everything in computers>internet>providers. Isn't that just a BETWEEN
> 'computers>internet>providers' AND 'computers>internet>providers>z'
> which a B+tree is supposed to handle just fine?

If I remember it well we had to do something like:
computers>internet>providers
adsl (20)
cable (31)
dial-up (107)
hosting (12)

So it was not simply a computers>internet>providers>adsl% , but
computers>internet>providers>adsl without
computers>internet>providers>adsl>%

> > I really don't know how much hardware you would like to use to get these
> > results?
>
> For DMOZ data I don't want hardware, I want GiST indexes:
> http://www.sai.msu.su/~megera/postgres/gist/ltree/

OpenLDAP could also work well I guess ;-)

Anyhow, the point I was trying to make was that it isn't just a question of
adding more hardware to get performance. More often than not a few
modifications will make a query pretty fast.
Yes, the query optimizer could be improved, but for a fast and reasonably
light DMS MySQL isn't bad at all!

Regards, Jigal.

Thread
Cost of joins?Margaret MacDonald9 Jul
  • Re: Cost of joins?Jigal van Hemert9 Jul
  • Re: Cost of joins?Martijn Tonies9 Jul
    • Re: Cost of joins?Alec.Cawley9 Jul
    • RE: Cost of joins?Lachlan Mulcahy12 Jul
      • Re: Cost of joins?Martijn Tonies12 Jul
      • Re: query gets count wrongGerald Taylor12 Jul
  • Re: Cost of joins?Alec.Cawley9 Jul
  • Re: Cost of joins?Jigal van Hemert9 Jul
    • Re: Cost of joins?Jochem van Dieten9 Jul
  • Re: Cost of joins?Martijn Tonies9 Jul
    • Re: Cost of joins?Alec.Cawley9 Jul
      • Re: Cost of joins?Jochem van Dieten9 Jul
    • Re: Cost of joins?(Michael Johnson)9 Jul
  • Re: Cost of joins?Jigal van Hemert9 Jul
  • Re: Cost of joins?Martijn Tonies9 Jul
RE: Cost of joins?Bob)9 Jul
Re: Cost of joins?Martijn Tonies9 Jul
Re: Cost of joins?Martijn Tonies9 Jul
Re: query gets count wrongSGreen12 Jul