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Re: Perform streaming logical transactions by background workers and parallel apply

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, "wangw.fnst@fujitsu.com" <wangw.fnst@fujitsu.com>, Peter Smith <smithpb2250@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, "shiy.fnst@fujitsu.com" <shiy.fnst@fujitsu.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-11-05T05:43:20Z
Lists: pgsql-hackers 
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 = 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?

-- 
With Regards,
Amit Kapila.

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Fix invalid memory access during the shutdown of the parallel apply worker.

  2. Fix assertion failure in apply worker.

  3. Use elog to report unexpected action in handle_streamed_transaction().

  4. Use appropriate wait event when sending data in the apply worker.

  5. Allow the logical_replication_mode to be used on the subscriber.

  6. Rename GUC logical_decoding_mode to logical_replication_mode.

  7. Display the leader apply worker's PID for parallel apply workers.

  8. Improve the code to decide and process the apply action.

  9. Document the newly added wait events added by commit 216a784829.

  10. Perform apply of large transactions by parallel workers.

  11. Wake up a subscription's replication worker processes after DDL.

  12. Add copyright notices to meson files

  13. Better document logical replication parameters

  14. Add a common function to generate the origin name.

  15. Harmonize parameter names in storage and AM code.

  16. Avoid using list_length() to test for empty list.

  17. Improve two comments related to a boolean DefElem's value

  18. Fix partition table's REPLICA IDENTITY checking on the subscriber.

  19. Fix data inconsistency between publisher and subscriber.

  20. Fix cache look-up failures while applying changes in logical replication.