Re: BUG #17540: Prepared statement: PG switches to a generic query plan which is consistently much slower

Setting aside the thread's subject, I am interested in this feature
because of its connection with the SJE feature and the same issue raised
[1] during the discussion.

Although the patch is already in a good state, some improvements can be
made. Look:
explain (costs off)
SELECT oid,relname FROM pg_class
WHERE oid < 5 OR (oid = 1 AND oid IS NULL);

  Bitmap Heap Scan on pg_class
    Recheck Cond: ((oid < '5'::oid) OR ((oid = '1'::oid) AND (oid IS NULL)))
    ->  BitmapOr
          ->  Bitmap Index Scan on pg_class_oid_index
                Index Cond: (oid < '5'::oid)
          ->  Bitmap Index Scan on pg_class_oid_index
                Index Cond: ((oid = '1'::oid) AND (oid IS NULL))

If we go deeply through the filter, I guess we could replace such buried
clauses.