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This patch adds a new SUBSCRIPTION parameter "origin". It specifies whether the subscription will request the publisher to only send changes that don't have an origin or send changes regardless of origin. Setting it to "none" means that the subscription will request the publisher to only send changes that have no origin associated. Setting it to "any" means that the publisher sends changes regardless of their origin. The default is "any". Usage: CREATE SUBSCRIPTION sub1 CONNECTION 'dbname=postgres port=9999' PUBLICATION pub1 WITH (origin = none); This can be used to avoid loops (infinite replication of the same data) among replication nodes. This feature allows filtering only the replication data originating from WAL but for initial sync (initial copy of table data) we don't have such a facility as we can only distinguish the data based on origin from WAL. As a follow-up patch, we are planning to forbid the initial sync if the origin is specified as none and we notice that the publication tables were also replicated from other publishers to avoid duplicate data or loops. We forbid to allow creating origin with names 'none' and 'any' to avoid confusion with the same name options. Author: Vignesh C, Amit Kapila Reviewed-By: Peter Smith, Amit Kapila, Dilip Kumar, Shi yu, Ashutosh Bapat, Hayato Kuroda Discussion: https://postgr.es/m/CALDaNm0gwjY_4HFxvvty01BOT01q_fJLKQ3pWP9=9orqubhjcQ@mail.gmail.com
The PostgreSQL contrib tree
---------------------------
This subtree contains porting tools, analysis utilities, and plug-in
features that are not part of the core PostgreSQL system, mainly
because they address a limited audience or are too experimental to be
part of the main source tree. This does not preclude their
usefulness.
User documentation for each module appears in the main SGML
documentation.
When building from the source distribution, these modules are not
built automatically, unless you build the "world" target. You can
also build and install them all by running "make all" and "make
install" in this directory; or to build and install just one selected
module, do the same in that module's subdirectory.
Some directories supply new user-defined functions, operators, or
types. To make use of one of these modules, after you have installed
the code you need to register the new SQL objects in the database
system by executing a CREATE EXTENSION command. In a fresh database,
you can simply do
CREATE EXTENSION module_name;
See the PostgreSQL documentation for more information about this
procedure.