Re: [PATCHES] Re: [HACKERS] Query->hasSubLinks is always FALSE...

Vadim B. Mikheev <vadim@sable.krasnoyarsk.su>

From: "Vadim B. Mikheev" <vadim@sable.krasnoyarsk.su>
To: Bruce Momjian <maillist@candle.pha.pa.us>
Cc: hackers@postgreSQL.org
Date: 1998-02-09T17:56:06Z
Lists: 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