Re: BUG #1118: Misleading Commit message

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: elein <elein(at)varlena(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, elein <elein(at)norcov(dot)com>, pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #1118: Misleading Commit message
Date: 2004-07-09 14:15:35
Message-ID: 200407091415.i69EFav01287@candle.pha.pa.us
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Do we want to add this to TODO:

* Issue an extra message when COMMIT completes an failed transaction

---------------------------------------------------------------------------

elein wrote:
>
>
>
> On Sun, Mar 28, 2004 at 10:23:26AM -0500, Tom Lane wrote:
> > Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > > PostgreSQL Bugs List wrote:
> > >> In a block transaction, whether or not there were errors in the transaction
> > >> issuing a commit; returns a COMMIT confirmation.
> >
> > > Uh, the tag indicates the COMMIT completed, not that it was a success.
> >
> > The current philosophy on command tags is "the tag is the same as the
> > command actually issued". However we are talking about breaking that
> > rule for EXECUTE, and if we do that, it's hard to say that we should
> > continue to enforce the rule for COMMIT. It would clearly be useful
> > for a COMMIT that ends a failed transaction to report ROLLBACK instead.
> >
> > > If we throw an error on a COMMIT, people willl think we did not close
> > > the transacction,
> >
> > ... which we wouldn't have. That won't work.
> >
> > > and if we return a ROLLBACK, they will think they issued a rollback.
> >
> > Which, in effect, is what they did. Is it likely that this would break
> > any clients? The intention of the current design rule is that clients
> > can match the tag against the command they issued, but I don't know of
> > any client code that actually does that.
> >
> > In any case, we already have some inconsistencies:
> >
> > regression=# begin;
> > BEGIN
> > regression=# end;
> > COMMIT
> > regression=# begin;
> > BEGIN
> > regression=# abort;
> > ROLLBACK
> > regression=#
> >
> > so it seems that in some cases we're already following a rule more like
> > "the tag is the same as the command actually *executed*".
> >
> > I started out not wanting to make this change either, but the more
> > I think about it the harder it is to hold that position.
> >
> > regards, tom lane
> >
> > ---------------------------(end of broadcast)---------------------------
> > TIP 3: if posting/reading through Usenet, please send an appropriate
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>
> The message could be something like:
> COMMIT: Transaction rolled back due to errors
>
> That way, it would reflect both the command and the action.
> But I am concerned about the information rather than
> the exact message if someone has better ideas.
>
> My reason for submitting the bug was as Tom stated:
> > It would clearly be useful
> > for a COMMIT that ends a failed transaction to report ROLLBACK instead.
>
> A commit that fails does not commit. It rolls back.
>
> In general, this would make it friendlier for new people and
> space cadets that don't notice the last statement failed :-)
>
> Elein
> elein(at)varlena(dot)com
>

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
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