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From:Eric Bergen Date:March 7 2005 6:16pm
Subject:Re: Join Limits
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The join table limit in MySQL is dictated by the arch that's running
on. 32 tables for 32bit and 64 tables for 64bit (Somebody correct me
if I'm wrong). I believe this is due to using a bitmap inside the join
optimizer to keep track of tables. 64 tables is a very hefty query it
makes me think that maybe you are doing something wrong when designing
your application to need a join that big. When the optimizer optimizes
a query it checks every possible execution path through every table so
the more joins you have the more paths the opimizer has to check to
find the optimal one (This isn't entirely true but close enough for my
argument here).

Needing more than 1024 columns in a table also seems like bad design.
Maybe you can detail more of what you are doing and why you need so
many columns

-Eric


On Mon, 7 Mar 2005 12:21:52 -0000, Kevin Cowley
<kevin.cowley@stripped> wrote:
> Does anyone know if there is a method of circumventing or changing the
> default join limits of 64 tables or 1024 columns? We're running Mysql
> 4.1.4 using MyISAM tables
> 
> Kevin Cowley
> Product Development
> Alchemetrics Ltd
> SMARTER DATA , FASTER
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-- 
Eric Bergen
eric.bergen@stripped
http://www.ebergen.net
Thread
Join LimitsKevin Cowley7 Mar
Re: Join LimitsEric Bergen7 Mar
RE: Join LimitsKevin Cowley7 Mar
Re: Join LimitsGreg Fortune7 Mar
  • Re: Join LimitsSGreen7 Mar