On Thu, Sep 23, 2021 at 10:33 PM Tomas Vondra <tomas.von...@enterprisedb.com> wrote: >
> 3) create_subscription.sgml > > <literal>WHERE</literal> clauses, rows must satisfy all expressions > to be copied. If the subscriber is a > > I'm rather skeptical about the principle that all expressions have to > match - I'd have expected exactly the opposite behavior, actually. > > I see a subscription as "a union of all publications". Imagine for > example you have a data set for all customers, and you create a > publication for different parts of the world, like > > CREATE PUBLICATION customers_france > FOR TABLE customers WHERE (country = 'France'); > > CREATE PUBLICATION customers_germany > FOR TABLE customers WHERE (country = 'Germany'); > > CREATE PUBLICATION customers_usa > FOR TABLE customers WHERE (country = 'USA'); > > and now you want to subscribe to multiple publications, because you want > to replicate data for multiple countries (e.g. you want EU countries). > But if you do > > CREATE SUBSCRIPTION customers_eu > PUBLICATION customers_france, customers_germany; > > then you won't get anything, because each customer belongs to just a > single country. Yes, I could create multiple individual subscriptions, > one for each country, but that's inefficient and may have a different > set of issues (e.g. keeping them in sync when a customer moves between > countries). > > I might have missed something, but I haven't found any explanation why > the requirement to satisfy all expressions is the right choice. > > IMHO this should be 'satisfies at least one expression' i.e. we should > connect the expressions by OR, not AND. > Fixed in V40 [1] ----- [1] https://www.postgresql.org/message-id/CAHut%2BPv-D4rQseRO_OzfEz2dQsTKEnKjBCET9Z-iJppyT1XNMQ%40mail.gmail.com Kind Regards, Peter Smith. Fujitsu Australia
