Re: [PATCHES] Re: [HACKERS] Query->hasSubLinks is always FALSE... - Mailing list pgsql-hackers

From Vadim B. Mikheev
Subject Re: [PATCHES] Re: [HACKERS] Query->hasSubLinks is always FALSE...
Date
Msg-id 34DF4336.B17928D5@sable.krasnoyarsk.su
Whole thread Raw
In response to Re: [PATCHES] Re: [HACKERS] Query->hasSubLinks is always FALSE...  (Bruce Momjian <maillist@candle.pha.pa.us>)
List pgsql-hackers
Bruce Momjian wrote:
>
> >
> > > me about two or three days to do the parser and rewrite for sublinks.
> > > How many coding days is the rest taking?  I am curious.
> >
> > All was near ready Feb 6, but ... I got problems from canonification
> > routines in optimizer: 'where A AND B OR C ' becomes 'where (A OR C) AND (B OR C)'
> > and if C is subselect then ... C has to be processed twice (sometime) ...
> > I remember your question about handling 'A AND (B OR SubSelect)' - unfortunately,
> > I didn't see problems here (actually, there is no problem with this
> > conjunctive normal form :), but there are troubles in common case.
> >
> > Ideas ?
> >
> > For the moment I could leave this un-optimized, with possibility
> > of double subselect processing...
>
> I would leave it for later.  We already have an optimizer explosion
> problem when we have lots of OR's so at some point we may have to
> revisit the cnf-ify process anyway.  Commerical Ingres has or had the
> same problem.

Ok, follow this way...

Vadim

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