Re: Bug with caching SQLTypes in Connection:getSQLType(oid)

I included a pretty chessy test case for this in the email. You'll have
to watch the log output with debug_query set to true in the postgresql
conf file. Look for the number of times the query is executed. With
the current cvs version, the query "select typname from pg_type where
oid = 1043" occurs four times. With my fix, it occurs once.
(args are url, username and password)

On Mon, 2001-12-10 at 12:43, Dave Cramer wrote:
> If we are going to try to get this in as a bug fix for 7.2RC1 then I
> would like to see something more conclusive.
>
> Can we verify that the patch works, or fixes something?
>
> Dave
>
> -----Original Message-----
> From: pgsql-jdbc-owner(at)postgresql(dot)org
> [mailto:pgsql-jdbc-owner(at)postgresql(dot)org] On Behalf Of Ned Wolpert
> Sent: Sunday, December 09, 2001 4:49 PM
> To: pgsql-jdbc(at)postgresql(dot)org
> Subject: Re: [JDBC] Bug with caching SQLTypes in
> Connection:getSQLType(oid)
>
>
> --- Antonio Fiol Bonnín <fiol(at)w3ping(dot)com> wrote:
> > Well, It is *certain* that the existing code is somehow broken. And it
> > is visible even at first sight. How to correct it is probably harder,
>
> Yes, I noticed that too. The 'quick/easy' fix that I'm using is to
> update sqlTypeCache hashtable which mapped 'oid -> SQLType'. That was
> the patch that I sent in. It doesn't break anything 'more' since a) if
> its not in cache it puts the value in the sqlTypeCache
> hashtable to begin with and b) if it is found in the check, then a
> potentially bogus result is returned. (Odds are it won't, since it
> currently checks typeOidCache, which maps 'PGType -> oid' instead. I
> doubt one would ever have an oid they send into the function, which
> would then check the typeOidCache. The oid key wouldn't match the
> PGType key to find the oid value. Ugh... my brain hurts... ;-)
>
> > but if you look into the following non abstract method,
> > getOID(String),
> > you will see that it is looking up in the same hashtable, but using a
> > different class.
>
> Yes. in getOID(String), it uses the typeOidCache correctly. (If the
> comments defining the variable typeOidCache are correct.) It maps the
> string of the PGType -> the Integer oid.
>
> > In getSQLType(int), it is looking up an entry for an
> > Integer. In getOID(String), it is looking up in the same hashtable,
> but
> > using a String. This is obviously wrong or a very bad programming
> > practice. (I vote wrong).
>
> Yeah, I think it was just a mistake made that didn't give incorrect
> results since the item is never cached. (Or, can never be found.)
>
> > I can't go much deeper by now. Sorry.
>
> Thanks, you've given me the info I need on the original discussion. I
> think we should see if we can put this fix in before 7.2 is released.
> Perchance in the 7.2rc1? Folks? Can someone else verify that our
> analysis is correct before the rc1 release?
>
> =====
> Virtually, | "Must you shout too?"
> Ned Wolpert | -Dante
> wolpert(at)yahoo(dot)com |
> _________________/ "Who watches the watchmen?"
> 4e75 -Juvenal, 120 AD
>
> -- Place your commercial here -- fnord
>
> __________________________________________________
> Do You Yahoo!?
> Send your FREE holiday greetings online! http://greetings.yahoo.com
>
> ---------------------------(end of broadcast)---------------------------
> TIP 6: Have you searched our list archives?
>
> http://archives.postgresql.org
>
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 2: you can get off all lists at once with the unregister command
> (send "unregister YourEmailAddressHere" to majordomo(at)postgresql(dot)org)
--

Virtually,
Ned Wolpert <ned(dot)wolpert(at)knowledgenet(dot)com>

D08C2F45: 28E7 56CB 58AC C622 5A51 3C42 8B2B 2739 D08C 2F45