Subject Indices and views
Author Christian G├╝tter
Hi,

I have got a query which joins two tables (B: T_Bestellungen;
P: T_Projekte) and generates the following plan:

PLAN SORT (JOIN (B NATURAL, P INDEX(RDB$PRIMARY16))).

The "natural" sort of B is ok, because B is a small table.
This runs quite fast.

Then I created a view (V) on table P and modified my query.
The query now joins table B and view V.
This time I got the following plan:

PLAN SORT (JOIN (B NATURAL, T_PROJEKTE NATURAL)).

This takes very long, because no index is used for P (T_Projekte).
I tried to feed the following plan to the optimizer:
PLAN (JOIN(B NATURAL, P INDEX(RDB$PRIMARY16))) but then I get
an error: "index RDB$PRIMARY16 cannot be used in the specified plan".

So why does the optimizer refuse my plan?
And why doesn't it choose the right index when I join the table
with a view?


TIA,

Christian