Re: Add CREATE support to event triggers

Robert Haas escribió:

> I think this direction has some potential. I'm not sure it's right in
> detail. The exact scheme you propose above won't work if you want to
> leave out the schema name altogether, and more generally it's not
> going to help very much with anything other than substituting in
> identifiers. What if you want to add a column called satellite_id to
> every table that gets created, for example? What if you want to make
> the tables UNLOGGED? I don't see how that kind of things is going to
> work at all cleanly.

Thanks for the discussion. I am building some basic infrastructure to
make this possible, and will explore ideas to cover these oversights
(not posting anything concrete yet because I expect several iterations
to crash and burn before I have something sensible to post).

> What I can imagine that might work is that you get a JSON blob for a
> create table statement and then you have a function
> make_a_create_table_statement(json) that will turn it back into SQL.
> You can pass a modified blob (adding, removing, or changing the
> schema_name or any other element) instead and it will do its thing.

I agree, except that I would prefer not to have one function for each
DDL statement type; instead we would have a single function that knows
to expand arbitrary strings using arbitrary JSON parameter objects, and
let ddl_rewrite.c (or whatever we call that file) deal with all the
ugliness.

One function per statement would increase the maintenance cost more, I
think (three extra pg_proc entries every time you add a new object type?
Ugh.)

--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services