Re: Perform streaming logical transactions by background workers and parallel apply
Peter Smith <smithpb2250@gmail.com>
Here are my review comments for v88-0002.
======
General
1.
The test cases are checking the log content but they are not checking
for debug logs or untranslated elogs -- they are expecting a normal
ereport LOG that might be translated. I’m not sure if that is OK, or
if it is a potential problem.
======
doc/src/sgml/config.sgml
2.
On the publisher side, logical_replication_mode allows allows
streaming or serializing changes immediately in logical decoding. When
set to immediate, stream each change if streaming option (see optional
parameters set by CREATE SUBSCRIPTION) is enabled, otherwise,
serialize each change. When set to buffered, the decoding will stream
or serialize changes when logical_decoding_work_mem is reached.
2a.
typo "allows allows" (Kuroda-san reported same)
2b.
"if streaming option" --> "if the streaming option"
~~~
3.
On the subscriber side, if streaming option is set to parallel,
logical_replication_mode also allows the leader apply worker to send
changes to the shared memory queue or to serialize changes.
SUGGESTION
On the subscriber side, if the streaming option is set to parallel,
logical_replication_mode can be used to direct the leader apply worker
to send changes to the shared memory queue or to serialize changes.
======
src/backend/utils/misc/guc_tables.c
4.
{
{"logical_replication_mode", PGC_USERSET, DEVELOPER_OPTIONS,
- gettext_noop("Controls when to replicate each change."),
- gettext_noop("On the publisher, it allows streaming or serializing
each change in logical decoding."),
+ gettext_noop("Controls the internal behavior of logical replication
publisher and subscriber"),
+ gettext_noop("On the publisher, it allows streaming or "
+ "serializing each change in logical decoding. On the "
+ "subscriber, in parallel streaming mode, it allows "
+ "the leader apply worker to serialize changes to "
+ "files and notifies the parallel apply workers to "
+ "read and apply them at the end of the transaction."),
GUC_NOT_IN_SAMPLE
},
Suggest re-wording the long description (subscriber part) to be more
like the documentation text.
BEFORE
On the subscriber, in parallel streaming mode, it allows the leader
apply worker to serialize changes to files and notifies the parallel
apply workers to read and apply them at the end of the transaction.
SUGGESTION
On the subscriber, if the streaming option is set to parallel, it
directs the leader apply worker to send changes to the shared memory
queue or to serialize changes and apply them at the end of the
transaction.
------
Kind Regards,
Peter Smith.
Fujitsu Australia
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