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Re: getObject()

From: Antonio Fiol Bonnín <fiol(at)w3ping(dot)com>
To: Rene Pijlman <rene(at)lab(dot)applinet(dot)nl>
Cc: pgsql-jdbc(at)postgresql(dot)org
Subject: Re: getObject()
Date: 2001-09-22 07:46:34
Message-ID: 3BAC41DA.31CB73BF@w3ping.com (view raw or flat)
Thread:
Lists: pgsql-jdbc
Rene Pijlman wrote:

> On Fri, 21 Sep 2001 17:26:20 +0200, you wrote:
> >When looking at the traffic that is going in and out of my machine, I
> >see many (a real lot of) times the same request. Something like:
> >
> >select typname from pg_type where oid = XXX
> >
> >where XXX is a number (23, 1184, or maybe others)
> >
> >As I use the getObject method to retrieve the different ocjects
> >contained in the resultset (I can't tell whether it's going to be an
> >number or a timestamp beforehand), I imagine that this select statement
> >is the one that helps getObject choose the right type. But, as every row
> >in the resultset will have the same column types, couldn't some caching
> >accelerate everything a lot?
>
> Looking at the source, I see signs of a caching mechanism in
> org.postgresql.Connection.getSQLType(), but at first glance it
> seems that this method doesn't actually add the type it
> retrieves to its own cache. That could very well be the cause of
> the problem.

That will help, probably.

> Do you intend to fix this yourself, or are you seeking help from
> this list? If so, it would be nice if you could post a small
> program that reproduces the problem. Its probably very simple,
> but that way we can be sure we're looking at the same problem.

I was going to try it myself. However, I have not been able to get the
current sources from CVS, as stated below. (I have just retried)


> >I have tried to connect to CVS, but instructions on
> >http://www.ca.postgresql.org/devel-corner/docs/postgres/cvs.html
> >did not work for me. I got:
> >cvs login: authorization failed: server postgresql.org rejected access
> >to /home/projects/pgsql/cvsroot for user anoncvs
>
> The CVS system is being migrated and there are lots of posts
> about it on the pgsql-hackers list. I'm not sure what the latest
> status is. The latest information should be on
> http://developer.postgresql.org/, but because of the recent
> shutdown of Great Bridge the system is in flux.

I used the information present on that site.

If you can have a look at it, what I do is a

select a::integer, b::timestamp, c::float from table;

and then I populate vectors by stating

myVectorA.add(rs.getObject("a"));

and the same for b and c.

table has quite a few rows (about 100 to 700, average 250).

When the code executes, if I start a network packet capture (after many
packets have already passed), I see the stated request about the types (and
presumably its response) going up and down.

I am using the precompiled driver for Java 1.2 found on
http://jdbc.fastcrypt.com.

Thank you very much if you may help, either by letting me access the current
source or by providing repaired binaries ;-)

Now seriously, I am willing to repair this, if possible.

Thanks.

Antonio


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