Thread

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

   Vadim B. Mikheev <vadim@sable.krasnoyarsk.su> — 1998-02-09T16:28:13Z

   Bruce Momjian wrote:
   > 
   > You know, after all our lengthy discussions, this SubLink thing looks
   > pretty clean to me.
   > 
   > How are subselects going?  Are you having to write a lot of code to get
   > it working?  I would say after all our discussions and thinking, it took
   
   Mmm ... =~ 1000 lines of code :)
   
   > 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...
   
   Vadim
   
   

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

   Bruce Momjian <maillist@candle.pha.pa.us> — 1998-02-09T17:33:59Z

   > 
   > Bruce Momjian wrote:
   > > 
   > > You know, after all our lengthy discussions, this SubLink thing looks
   > > pretty clean to me.
   > > 
   > > How are subselects going?  Are you having to write a lot of code to get
   > > it working?  I would say after all our discussions and thinking, it took
   > 
   > Mmm ... =~ 1000 lines of code :)
   > 
   > > 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.
   
   
   -- 
   Bruce Momjian
   maillist@candle.pha.pa.us
   
   

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

   Vadim B. Mikheev <vadim@sable.krasnoyarsk.su> — 1998-02-09T17:56:06Z

   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