On Tue, Dec 6, 2022 at 9:29 PM Amit Kapila <amit.kapil...@gmail.com> wrote: > > On Tue, Dec 6, 2022 at 11:53 AM shiy.f...@fujitsu.com > <shiy.f...@fujitsu.com> wrote: > > > > Hi hackers, > > > > In logical decoding, when logical_decoding_work_mem is exceeded, the > > changes are > > sent to output plugin in streaming mode. But there is a restriction that the > > minimum value of logical_decoding_work_mem is 64kB. I tried to add a GUC to > > allow sending every change to output plugin without waiting until > > logical_decoding_work_mem is exceeded. > > > > This helps to test streaming mode. For example, to test "Avoid streaming the > > transaction which are skipped" [1], it needs many XLOG_XACT_INVALIDATIONS > > messages. With the new option, it can be tested with fewer changes and in > > less > > time. Also, this new option helps to test more scenarios for "Perform > > streaming > > logical transactions by background workers" [2]. > >
+1 > > Yeah, I think this can also help in reducing the time for various > tests in test_decoding/stream and > src/test/subscription/t/*_stream_*.pl file by reducing the number of > changes required to invoke streaming mode. Can we think of making this > GUC extendible to even test more options on server-side (publisher) > and client-side (subscriber) cases? For example, we can have something > like logical_replication_mode with the following valid values: (a) > server_serialize: this will serialize each change to file on > publishers and then on commit restore and send all changes; (b) > server_stream: this will stream each change as currently proposed in > your patch. Then if we want to extend it for subscriber-side testing > then we can introduce new options like client_serialize for the case > being discussed in the email [1]. > > Thoughts? There is potential for lots of developer GUCs for testing/debugging in the area of logical replication but IMO it might be better to keep them all separated. Putting everything into a single 'logical_replication_mode' might cause difficulties later when/if you want combinations of the different modes. For example, instead of logical_replication_mode = XXX/YYY/ZZZ maybe something like below will give more flexibility. logical_replication_dev_XXX = true/false logical_replication_dev_YYY = true/false logical_replication_dev_ZZZ = true/false ------ Kind Regards, Peter Smith. Fujitsu Australia