On Aug 26, 2008, at 8:24 AM, ml wrote:
>
>> thats a bug which was fixed post 0.4.7p1. Its in trunk and is for
>> 0.4.8.
>
> Great!
>
> And back to the mapper properties. As I found it always do a
> polymorphic_fetch=select-like query when dealing with mapper
> properties
> referencing a polymorphic base. This is not very efficient. I would
> prefer an union fetch. I realized that it is similar to query().get().
> Example follows:
>
> session.query(Base).with_polymorphic("*").filter(Base.id==3).first().x
>
> results in 1 joined select:
> SELECT base.id AS base_id, base.id_parent AS base_id_parent, base.kind
> AS base_kind, derived.id AS derived_id, derived.x AS derived_x,
> derived.id_other AS derived_id_other
> FROM base LEFT OUTER JOIN derived ON derived.id = base.id
> WHERE base.id = ? ORDER BY base.oid
> LIMIT 1 OFFSET 0
>
> but session.query(Base).with_polymorphic("*").get(3).x
>
> results in 2 selects:
> SELECT base.id AS base_id, base.id_parent AS base_id_parent, base.kind
> AS base_kind
> FROM base
> WHERE base.id = ?
> SELECT derived.x AS derived_x, derived.id_other AS derived_id_other
> FROM base JOIN derived ON derived.id = base.id
> WHERE base.id = ?
>
> Both queries gives the same object but the get() generates 2 selects
> (like the mapper property fetch). Why?
yup..this is one of many things inheritance related that works
properly in 0.5....
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