On Saturday, November 5, 2022 1:43 PM Amit Kapila <amit.kapila16@gmail.com>
>
> On Fri, Nov 4, 2022 at 7:35 PM houzj.fnst@fujitsu.com
> <houzj.fnst@fujitsu.com> wrote:
> >
> > On Friday, November 4, 2022 4:07 PM Amit Kapila
> <amit.kapila16@gmail.com> wrote:
> > >
> > > On Thu, Nov 3, 2022 at 6:36 PM houzj.fnst@fujitsu.com
> > > <houzj.fnst@fujitsu.com> wrote:
> > > >
> > > > Thanks for the analysis and summary !
> > > >
> > > > I tried to implement the above idea and here is the patch set.
> > > >
> > >
> > > Few comments on v42-0001
> > > ===========================
> >
> > Thanks for the comments.
> >
> > >
> > > 10.
> > > + winfo->shared->stream_lock_id = parallel_apply_get_unique_id();
> > > + winfo->shared->transaction_lock_id =
> > > + winfo->shared->parallel_apply_get_unique_id();
> > >
> > > Why can't we use xid (remote_xid) for one of these and local_xid
> > > (one generated by parallel apply) for the other?
> ...
> ...
> >
> > I also considered using xid for these locks, but it seems the objsubid
> > for the shared object lock is 16bit while xid is 32 bit. So, I tried
> > to generate a unique 16bit id here.
> >
>
> Okay, I see your point. Can we think of having a new lock tag for this with classid,
> objid, objsubid for the first three fields of locktag field? We can use a new
> macro SET_LOCKTAG_APPLY_TRANSACTION and a common function to set the
> tag and acquire the lock. One more point related to this is that I am suggesting
> classid by referring to SET_LOCKTAG_OBJECT as that is used in the current
> patch but do you think we need it for our purpose, won't subscription id and
> xid can uniquely identify the tag?
I agree that it could be better to have a new lock tag. Another point is that
the remote xid and Local xid could be the same in some rare cases, so I think
we might need to add another identifier to make it unique.
Maybe :
locktag_field1 : subscription oid
locktag_field2 : xid(remote or local)
locktag_field3 : 0(lock for stream block)/1(lock for transaction)
Best regards,
Hou zj
