ActiveRecord, Postgres and partitioned tables

I've set up a trigger-based partitioning scheme on one of our pg 8.3 databases 开发者_如何学运维according to the pg docs here:. Basically, I have a parent table, along with several child tables. An insert trigger on the parent redirects any inserts on the parent into the appropriate child table -- this works well.

The ActiveRecord pg adapter, however, seems to rely on the postgres INSERT ... RETURNING "id" extension to get the id of the returned row after the initial insert. But the trigger seems to break the RETURNING clause -- no id is returned, although the row is created correctly.

While I suppose this behavior makes sense -- after all, nothing is being inserted in the main table, I really need to find some kind of work-around, as other child records will be inserted that require the row id of the just-inserted row.

I suppose I could add some kind of unique id to row prior to insert and then re-read it using this key after insert, but this seems pretty kludgy. Does anyone have a better work-around?

Since Rails v.2.2.1, you can turn off 'returning id' behavior just by overriding #supports_insert_with_returning method in PostgreSQLAdapter.

class ActiveRecord::ConnectionAdapters::PostgreSQLAdapter
  def supports_insert_with_returning?
    false
  end
end

Currently it looks like my best option is to just change the table prefix in a before_create event so that the insert happens on the underlying partition table directly, bypassing the insert trigger altogether. This is not a perfect solution, however, but seems to be the most performant and the simplest.

The only other solution I can come up with is to add a guid column to each table, and re-read the row from the parition table by guid immediately after insert to get the id.

Any other suggestions are welcome. Thanx -- m