Tom Lane wrote:
> Simon Riggs <simon@2ndquadrant.com> writes:
> > pg_am has existed for decades without supporting DDL
>
> That argument has been obsoleted by events ;-) ... and in any case, the
> reason we went without CREATE ACCESS METHOD for so long was not that we
> encouraged "INSERT INTO pg_am" but that non-core index AMs were
> effectively unsupported anyway, until we thought of a reasonable way to
> let them generate WAL. Without the WAL stumbling block, I'm sure we would
> have built CREATE ACCESS METHOD long ago.
Note that the alternative to DDL-based replication handling is not
INSERT INTO pg_replication, but a function-based interface such as
SELECT pg_replication_node_create(foo, bar); so there's no need to
hardcode catalog definitions; nor there is a need to skip backup-ability
of logical replication config: pg_dump support can be added by having it
output function calls -- not catalog INSERTs!
The only difference between DDL and no DDL is that a function-based
interface can be added with a few pg_proc.h entries, whereas the DDL
stuff requires gram.y additions, new nodes, etc.
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
