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From:Benjamin Pflugmann Date:June 7 2002 1:50am
Subject:Re: Maximum JOINED tables
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Hi.

On Thu 2002-06-06 at 19:17:10 +0200, roger.baklund@stripped wrote:
[...]

> But... is this the only feature of mysql which is dependant on the
> processor architecture?

See it the other way: You are not garantueed more than 31 tables in a
join. If you happen to have a 64Bit architecture, you can use more.

> I'm kind of nervous about this, because I'm currently working on a 'very
> normalized' database schema, and it is possible I will need more than 31
> tables in a single select... including multiple joins to the same tables, of
> course. It would be very bad if my design turned out to be 64-bit
> dependant...

AFAIK, if you need so many tables, you get a major problem: MySQL
figures out the best join order by trying all combinations. This
becomes increasingly slow as you are going to join more tables. In
other words: Trying to use 30 tables in one select probably will be
too slow as that it would matter whether so many tables are allowed in
a join or not.

Of course, you could work around it by using STRAIGHT_JOIN, but I
assume it is to cumbersome to figure out the optimal join order for
all SELECTs.

Bye,

	Benjamin.

-- 
benjamin-mysql@stripped
Thread
Maximum JOINED tablesArthur Fuller5 Jun
  • Re: Maximum JOINED tablesRoger Baklund5 Jun
RE: Maximum JOINED tablesWalt Weaver5 Jun
  • RE: Maximum JOINED tablesAndrew Hazen5 Jun
RE: Maximum JOINED tablesWalt Weaver5 Jun
RE: Maximum JOINED tablesWalt Weaver5 Jun
  • Re: Maximum JOINED tablesSabine Richter5 Jun
    • Re: Maximum JOINED tablesDan Nelson5 Jun
  • Re: Maximum JOINED tablesRoger Baklund5 Jun
    • Re: Maximum JOINED tablesHarald Fuchs6 Jun
      • RE: Maximum JOINED tablesRoger Baklund6 Jun
        • Re: RE: Maximum JOINED tablesVictoria Reznichenko6 Jun
          • Re: Maximum JOINED tablesRoger Baklund6 Jun
            • Re: Maximum JOINED tablesBenjamin Pflugmann7 Jun
              • Re: Maximum JOINED tablesRoger Baklund7 Jun
                • Re: Re: Maximum JOINED tablesVictoria Reznichenko7 Jun
                  • Re: Maximum JOINED tablesRoger Baklund7 Jun
                • Re: Maximum JOINED tablesBenjamin Pflugmann7 Jun
                  • Re: Maximum JOINED tablesRoger Baklund8 Jun
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                        • RE: Not using indexes???Jon Frisby8 Jun
                          • Re: Not using indexes???Benjamin Pflugmann8 Jun
                            • Re: Not using indexes???Erv Young10 Jun
                            • RE: Not using indexes???Jon Frisby10 Jun
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