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Re: Can PostgreSQL do data type automated casting in

From: Mark Lewis <mark(dot)lewis(at)mir3(dot)com>
To: Kris Jurka <books(at)ejurka(dot)com>
Cc: Tjioe Ai Xin <xinxincute(at)gmail(dot)com>, pgsql-jdbc(at)postgresql(dot)org
Subject: Re: Can PostgreSQL do data type automated casting in
Date: 2005-11-21 23:37:26
Message-ID: 1132616246.4154.10.camel@archimedes (view raw, whole thread or download thread mbox)
Lists: pgsql-jdbc
Here's a thought; do you think it's feasible to detect cases where the
protocol=3 driver throws an error due to invalid or ambiguous typing
issues when the protocol=2 driver would just do the expected thing?

Instead of throwing the error back to the user, could the driver then
issue a 'describe statement' call, use the result to disambiguate the
parameter settings, and re-issue the call?  It increases the overhead
but only for the error cases, and the result could be cached to avoid
repeating that overhead.

I haven't done any hacking in the driver yet, so maybe it would be too
much of a pain to implement to justify any possible gains.

-- Mark Lewis

On Mon, 2005-11-21 at 18:08 -0500, Kris Jurka wrote:
> On Mon, 21 Nov 2005, Tjioe Ai Xin wrote:
> >
> > My code is like this: I have query: "Select count(*) / paramPage from 
> > tblFirst where condition"; The paramPage were filled from parameter 
> > which I specified as string data type. So I using setString method for 
> > my prepared statement for passing paramPage value. When I'm using the 
> > old jdbc driver pg74jdbc3.jar, I got no problem at all. But when I try 
> > to upgrade my PostgreSQL to 8.0.3. I got problem data type error.
> >
> > Can PostgreSQL do data type automated casting in prepared statement again?
> > So I do not need change my code :)
> >
> Yes, and no.  You can restore the old behavior by adding 
> ?protocolVersion=2 to your connection URL, but using the older protocol 
> also means some new features and performance gains will be unavailable to 
> you.
> Kris Jurka
> ---------------------------(end of broadcast)---------------------------
> TIP 6: explain analyze is your friend

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