Re: Perform streaming logical transactions by background workers and parallel apply
Amit Kapila <amit.kapila16@gmail.com>
On Fri, Nov 11, 2022 at 7:57 AM houzj.fnst@fujitsu.com
<houzj.fnst@fujitsu.com> wrote:
>
> On Monday, November 7, 2022 6:18 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> >
> > Here are comments on v42-0001:
> >
> > We have the following three similar name functions regarding to
> > starting a new parallel apply worker:
> > ---
> > /*
> > * Exit if any parameter that affects the remote connection
> > was changed.
> > - * The launcher will start a new worker.
> > + * The launcher will start a new worker, but note that the
> > parallel apply
> > + * worker may or may not restart depending on the value of
> > the streaming
> > + * option and whether there will be a streaming transaction.
> >
> > In which case does the parallel apply worker don't restart even if the
> > streaming option has been changed?
>
> Sorry, I forgot to reply to this comment. If user change the streaming option from
> 'parallel' to 'on' or 'off', the parallel apply workers won't be restarted.
>
How about something like the below so as to be more explicit about
this in the comments?
diff --git a/src/backend/replication/logical/worker.c
b/src/backend/replication/logical/worker.c
index bfe326bf0c..74cd5565bd 100644
--- a/src/backend/replication/logical/worker.c
+++ b/src/backend/replication/logical/worker.c
@@ -3727,9 +3727,10 @@ maybe_reread_subscription(void)
/*
* Exit if any parameter that affects the remote connection was changed.
- * The launcher will start a new worker, but note that the
parallel apply
- * worker may or may not restart depending on the value of the streaming
- * option and whether there will be a streaming transaction.
+ * The launcher will start a new worker but note that the parallel apply
+ * worker won't restart if the streaming option's value is changed from
+ * 'parallel' to any other value or the server decides not to stream the
+ * in-progress transaction.
*/
--
With Regards,
Amit Kapila.
Commits
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the thread's linked commits as JSON, with link sources.
API reference →
-
Fix invalid memory access during the shutdown of the parallel apply worker.
- 3d144c6c8602 16.0 landed
-
Fix assertion failure in apply worker.
- de63f8dadee4 16.0 landed
-
Use elog to report unexpected action in handle_streamed_transaction().
- 781ac42d43ab 16.0 landed
-
Use appropriate wait event when sending data in the apply worker.
- d9d7fe68d35e 16.0 landed
-
Allow the logical_replication_mode to be used on the subscriber.
- 9f2213a7c575 16.0 landed
-
Rename GUC logical_decoding_mode to logical_replication_mode.
- 1e8b61735cfb 16.0 landed
-
Display the leader apply worker's PID for parallel apply workers.
- d540a02a724b 16.0 landed
-
Improve the code to decide and process the apply action.
- c981d9145dea 16.0 landed
-
Document the newly added wait events added by commit 216a784829.
- cd06ccd78fcf 16.0 landed
-
Perform apply of large transactions by parallel workers.
- 216a784829c2 16.0 landed
-
Wake up a subscription's replication worker processes after DDL.
- c6e1f62e2cee 16.0 cited
-
Add copyright notices to meson files
- 8284cf5f746f 16.0 cited
-
Better document logical replication parameters
- a8500750ca0a 16.0 cited
-
Add a common function to generate the origin name.
- 776e1c8a5d14 16.0 cited
-
Harmonize parameter names in storage and AM code.
- bfcf1b34805f 16.0 cited
-
Avoid using list_length() to test for empty list.
- efd0c16becbf 16.0 cited
-
Improve two comments related to a boolean DefElem's value
- 8445f5a21d40 16.0 cited
-
Fix partition table's REPLICA IDENTITY checking on the subscriber.
- 26b3455afaa9 15.0 cited
-
Fix data inconsistency between publisher and subscriber.
- b7658c24c7c1 15.0 cited
-
Fix cache look-up failures while applying changes in logical replication.
- 5a97b1325453 15.0 cited