> On Jun 2, 2026, at 14:14, Amit Kapila <[email protected]> wrote: > > On Mon, Jun 1, 2026 at 6:42 PM Chao Li <[email protected]> wrote: >> >> While testing “Support existing publications in pg_createsubscriber”, I >> noticed that it doesn’t allow the same publication name even when the >> publications are from different databases. >> >> A simple repro: >> ``` >> % createdb db1 >> % createdb db2 >> % psql db1 -c 'CREATE PUBLICATION app_pub FOR ALL TABLES' >> % psql db2 -c 'CREATE PUBLICATION app_pub FOR ALL TABLES' >> CREATE PUBLICATION >> CREATE PUBLICATION >> % pg_createsubscriber --dry-run --pgdata <data-dir> --publisher-server >> postgres --database db1 --database db2 --publication app_pub --publication >> app_pub >> pg_createsubscriber: error: publication "app_pub" specified more than once >> for --publication >> ``` >> >> The rejection is not introduced by this feature, but previously it was not a >> real problem because the specified publication names would always be >> created. After this feature, it may become an issue, since the feature >> intends to use existing publications, and users may have defined >> publications with the same name in different databases. So the current >> restriction becomes a limitation of the new feature. I don’t think we should >> leave this limitation in PG19. >> >> Since pg_createsubscriber already ensures that duplicate database names >> cannot be specified, we can just remove the duplicate publication name check. >> > > Doesn't the same point apply to subscription names? The subscription > names can be specified by "--subscription=name" > > -- > With Regards, > Amit Kapila.
In theory, yes, since subscription names are also unique per database. I didn’t include that in v1 because the publication-name issue affects the new PG19 feature for reusing existing publications, whereas allowing duplicate subscription names seems like an improvement that could be a material of v20. As you ask, I put the subscription-name change in 0002. Please decide how to proceed. If you decide to accept both, they can be squashed. Best regards, -- Chao Li (Evan) HighGo Software Co., Ltd. https://www.highgo.com/
v2-0001-pg_createsubscriber-allow-duplicate-publication-n.patch
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v2-0002-pg_createsubscriber-Allow-duplicate-subscription-.patch
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