Re: FOR SHARE vs FOR UPDATE locks

On 12/1/06, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com> writes:
> > Let's throw an error for now. We have to come back to this in 8.3, I think.
>
> After further thought I think we should also seriously consider plan C:
> do nothing for now. We now realize that there have been related bugs
> since 8.0, namely that
>
> begin;
> select some rows for update;
> savepoint x;
> update the same rows;
> rollback to x;
>
> leaves the tuple(s) not locked. The lack of complaints about this from
> the field suggests that this isn't a huge problem in practice. If we
> do make it throw an error I'm afraid that we will break applications
> that aren't having a problem at the moment.

imo, the most likely scenario would be a begin/exception/end block in
pg/sql. i would venture to guess that very little true savepointing
happens in practice. maybe add a little note of caution pg/sql error
handling documentation?

merlin