Subject Re: [ib-support] query plan
Author Helen Borrie
At 10:15 PM 29/04/2003 -0300, you wrote:
>i have this query:
>from cuenta cu
>join notificacion nt on nt.id_cuenta = cu.id_cuenta
>and i get this plan:
>table cuenta has a pk on id_cuenta
>table notificacion has a fk on id_cuenta
>why optimizer choses natural instead fk on notificacion?
>is related to record count?

Yes. If the FK index has low selectivity, or notificacion table has not
many rows, the optimizer may calculate that a scan will be faster than
using the index.