Re: database design method

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 Thu Nov 14 2002 - 01:35:47 CET