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Re: database design method

From: Mikito Harakiri <mikharakiri_at_yahoo.com>
Date: 13 Nov 2002 16:35:47 -0800
Message-ID: <bdf69bdf.0211131635.48b3ac72@posting.google.com>


hidders_at_hcoss.uia.ac.be (Jan Hidders) wrote in message news:<3dd12e86$1_at_news.uia.ac.be>...
> > But how on earth does the optimiser handle this
> >query besides materialising the whole tree?
>
> By pushing the selection into the recursion and using a query optimization
> technique called "magic sets".

Consider a simple recursion example:

with iota (n) as
( values(1)

   union all
  select n+1 from iota
  where n<100000
)
select * from iota where n*n=25;

Could n*n=25 predicate be pushed into the recursion? When a predicate can be pushed into recursion? Received on Wed Nov 13 2002 - 18:35:47 CST

Original text of this message

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