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Re: PL/Perl list value return causes segfault

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Andrew Dunstan <andrew(at)dunslane(dot)net>
Cc: David Fetter <david(at)fetter(dot)org>,Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>,Michael Fuhr <mike(at)fuhr(dot)org>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: PL/Perl list value return causes segfault
Date: 2005-07-30 03:24:37
Message-ID: 200507300324.j6U3Ob713189@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-docspgsql-hackerspgsql-patches
Would someone who knows perl update plperl.sgml and send me a patch?

Also, is this still true in 8.1:

      In the current implementation, if you are fetching or returning
      very large data sets, you should be aware that these will all go
      into memory.


---------------------------------------------------------------------------

Andrew Dunstan wrote:
> 
> 
> David Fetter wrote:
> 
> >On Tue, Jul 12, 2005 at 03:45:55PM -0400, Andrew Dunstan wrote:
> >  
> >
> >>
> >>In perl, if there is any ambiguity it is the called function that is
> >>responsible for checking, not the caller. See "perldoc -f
> >>wantarray".  PLPerl explicitly passed G_SCALAR as a flag on all
> >>calls to plperl routines. So returning a list is a case of pilot
> >>error.
> >>    
> >>
> >
> >Is this a kind of pilot error that documents could help avert in some
> >useful way?
> >
> >
> >  
> >
> 
> Sure. "A plperl function must always return a scalar value.More complex 
> structures (arrays, records, and sets) can be returned in the 
> appropriate context by returning a reference. A list should never be 
> returned."  Salt to taste and insert where appropriate.
> 
> cheers
> 
> andrew
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 9: In versions below 8.0, the planner will ignore your desire to
>        choose an index scan if your joining column's datatypes do not
>        match
> 

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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