On Sat, May 22, 2021 at 1:49 AM Mark Dilger <mark.dil...@enterprisedb.com> wrote: > > -hackers, > > I think commit 82ed7748b710e3ddce3f7ebc74af80fe4869492f created some > confusion that should be cleaned up before release. I'd like some guidance > on what the intended behavior is before I submit a patch for this, though: > > +ALTER SUBSCRIPTION mysubscription SET PUBLICATION nosuchpub WITH (copy_data > = false, refresh = false); > +ALTER SUBSCRIPTION mysubscription ADD PUBLICATION nosuchpub WITH (copy_data > = false, refresh = false); > +ALTER SUBSCRIPTION mysubscription DROP PUBLICATION nosuchpub WITH (copy_data > = false, refresh = false); > +ERROR: unrecognized subscription parameter: "copy_data" > +ALTER SUBSCRIPTION mysubscription SET (copy_data = false, refresh = false); > +ERROR: unrecognized subscription parameter: "copy_data" > > First, it's quite odd to say that "copy_data" is unrecognized in the third > and fourth ALTER commands when it was recognized just fine in the first two.
For ALTER SUBSCRIPTION ... DROP PUBLICATION, copy_data option is not required actually, because it doesn't add new publications. If the concern here is "why refresh is allowed but not copy_data", then the answer is "with the refresh option the updated publications can be refreshed, this avoids users to run REFRESH PUBLICATION after DROP PUBLICATION". So, disallowing copy_data makes sense to me. For ALTER SUBSCRIPTION ... SET, allowed options are slot_name, synchronous_commit, binary and streaming which are part of pg_subscription catalog and will be used by apply/sync workers. Whereas copy_data and refresh are not part of pg_subscription catalog and are not used by apply/sync workers (directly), but by the backend. We have ALTER SUBSCRIPTION .. REFRESH specifically for refresh and copy_data options. > More than that, though, the docs in doc/src/sgml/ref/alter_subscription.sgml > refer to this part of the grammar in the first three ALTER commands as a > "set_publication_option", not as a "subscription_parameter", a term which is > only used in the grammar for other forms of the ALTER command. Per the > grammar in the docs, "copy_data" is not a valid set_publication_option, only > "refresh" is. set_publication_option - options are refresh and copy_data (this option comes implicitly, please see the note "Additionally, refresh options as described under REFRESH PUBLICATION may be specified.", under refresh_option we have copy_data) subscription_parameter - options are slot_name, synchronous_commit, binary, and streaming. This is correct. > Should the first three ALTER commands fail with an error about "copy_data" > being an invalid set_publication_option? Should they succeed, in which case > the docs should mention that "refresh" is not the only valid > set_publication_option? No that's not correct. As I said above, set_publication_option options are both refresh and copy_data. > Something else, perhaps? Unless I misunderstood any of your concerns, I think the existing docs and the code looks correct to me. With Regards, Bharath Rupireddy. EnterpriseDB: http://www.enterprisedb.com
