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Re: Undocumented feature costs a lot of performance in COPY

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Gavin Sherry <swm(at)linuxworld(dot)com(dot)au>
Cc: pgsql-patches(at)postgresql(dot)org
Subject: Re: Undocumented feature costs a lot of performance in COPY
Date: 2002-01-05 02:28:32
Message-ID: 200201050228.g052SWl29858@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
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Gavin Sherry wrote:
> On Fri, 28 Dec 2001, Bruce Momjian wrote:
> 
> > > Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > > > We could support keywords DELIMITER and DELIMITERS and only document
> > > > the first one.
> > > 
> > > One could also argue that it should be WITH DELIMITER for more
> > > consistency with the other optional clauses.
> > > 
> > > But let's put that in the TODO list, not try to get it done now...
> > 
> > Updated TODO:
> > 
> > COPY
> > 	...
> >         o Change syntax to WITH DELIMITER, (keep old syntax around?)
> > 
> 
> An attached patch implements this. The problem with implementing this is
> that the new syntax is:
> 
> 	.... WITH DELIMITERS '<delim>' WITH NULL AS '<char>'
> 
> Naturally, this leads to a shift/reduce conflict. Solution is more or less
> that used with CREATE DATABASE WITH ... WITH ... etc. The only ugly bit
> was mixing this with the old USING DELIMITERS ... syntax. I don't like the
> solution -- I get the feeling there's a better way to do it. 
> 
> The other option of course is to update yylex() to create a new token
> in the same way that the UNIONJOIN terminal is created. But I think this
> is a bit messy.
> 
> Ideas or is this okay?
> 
> Gavin

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-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

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