Re: [PATCHES] allow CSV quote in NULL

Added to TODO for COPY:
     o Allow COPY in CSV mode to control whether "" is treated as NULL
       http://archives.postgresql.org/pgsql-hackers/2007-07/msg00905.php


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Andrew Dunstan wrote:
> 
> [redirecting to -hackers]
> 
> Stephen Frost wrote:
> > * Gregory Stark (stark@enterprisedb.com) wrote:
> >   
> >> "Tom Lane" <tgl@sss.pgh.pa.us> writes:
> >>
> >>     
> >>> Stephen Frost <sfrost@snowman.net> writes:
> >>>       
> >>>>   Please find attached a minor patch to remove the constraints that a
> >>>>   user can't include the delimiter or quote characters in a 'NULL AS'
> >>>>   string when importing CSV files.
> >>>>         
> >>> This can't really be sane can it?
> >>>       
> >   
> 
> Not very, no :-)
> >   
> >> The alternative would be interpreting NULL strings after dequoting but that
> >> would leave no way to include the NULL string literally. This solution means
> >> there's no way to include it (if it needs quoting) but only when you specify
> >> it this way.
> >>     
> >
> > Yeah, interpreting NULLs after dequoting means you've lost the
> > information about if it's quoted or not, or you have to add some funky
> > syntax to say "if it's quoted, do it differently...", which is no good,
> > imv.
> >
> > What the patch does basically is say "give us the exact string that
> > shows up between the unquoted delimiters that you want to be treated
> > as a NULL."  This removes the complexity of the question about quoting,
> > unquoting, whatever, and makes it a very clear-cut, straight-forward
> > solution with no impact on existing users, imv.
> >
> >     
> >   
> 
> This looks too clever by half, to me. Someone facing the problem you are 
> facing would have to dig quite deep to find the solution you're promoting.
> 
> A much better way IMNSHO would be to add an extra FORCE switch. On 
> input, FORCE NOT NULL says to treat an unquoted null as the literal 
> value rather than as a null field for the columns named. The reverse 
> would be to tell it to treat a quoted null as null rather than as the 
> literal value, for the named columns. Perhaps that should just be "FORCE 
> NULL columnlist". It would be more explicit and at the same time would 
> only apply to the named columns, rather than discarding totally the 
> ability to distinguish between null and not null values.
> 
> This should probably be discussed on -hackers, anyway.
> 
> 
> 
> cheers
> 
> andrew
> 
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--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://postgres.enterprisedb.com
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