From: Bruce Momjian <pgman@candle.pha.pa.us>
Message-Id: <200106121809.f5CI98q28375@candle.pha.pa.us>
Subject: Re: remote database queries
In-Reply-To: <009101c0e98e$872bdb00$0205a8c0@jecw2k1> "from Joe Conway at May
	30, 2001 09:59:52 pm"
To: Joe Conway <joe.conway@mail.com>
Date: Tue, 12 Jun 2001 14:09:08 -0400 (EDT)
CC: pgsql-hackers@postgresql.org
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Your patch has been added to the PostgreSQL unapplied patches list at:

	http://candle.pha.pa.us/cgi-bin/pgpatches

I will try to apply it within the next 48 hours.

> > Until we fix that (maybe for 7.2, maybe not) your existing hack is
> > probably pretty reasonable.  You could save some cycles by avoiding
> > conversion to text, though --- instead return an opaque datum that is
> > pointer-to-tuple-slot and let the dblink_tok function extract fields
> > from the tuple.  Look at SQL function support and the FieldSelect
> > expression node type for inspiration.
> >
> 
> I changed the dblink() function to return a pointer instead of concatenated
> text, and dblink_tok() to use the pointer. FWIW, a query on a small (85
> tuples) remote (a second PC on a 100baseT subnet) table takes about 34
> milliseconds (based on show_query_stats) versus about 4 milliseconds when
> run locally. It actually takes a bit longer (~65 milliseconds) when run
> against a second database on the same PC. The original text parsing version
> was about 25% slower.
> 
> Although shifting from text parsing to pointer passing is more efficient, I
> have one more question regarding this -- for now ;) -- is there any way to
> check the pointer passed to dblink_tok() to be sure it came from dblink()?
> 
> Thanks,
> 
> -- Joe
> 

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-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
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