>
>    In case of RelatedJoins SQLObject deletes objects from the intermediate
> table itself because the table can be hidden from the user at all - it is
> usually automatically created and maintained.
>

Ok, I just realized that my example was bad. This one's better:

class Top(sqlobject.SQLObject):
    a = sqlobject.SQLMultipleJoin('A')

class AB(sqlobject.SQLObject):
    a = sqlobject.ForeignKey('A', cascade = True)
    b = sqlobject.ForeignKey('B', cascade = True)
   
class A(sqlobject.SQLObject):
    top = sqlobject.ForeignKey('Top', cascade = True)
    b   = sqlobject.RelatedJoin('B', intermediateTable = AB.sqlmeta.table, createRelatedTable = False)

class B(sqlobject.SQLObject):
    a = sqlobject.RelatedJoin('A', intermediateTable = AB.sqlmeta.table, createRelatedTable = False)
   

   
Top.createTable(ifNotExists = True)
A.createTable(ifNotExists = True)
B.createTable(ifNotExists = True)
AB.createTable(ifNotExists = True)

[a.destroySelf() for a in A.select()]
[b.destroySelf() for b in B.select()]
[ab.destroySelf() for ab in AB.select()]


top = Top()

a1 = A(top = top)
a2 = A(top = top)
a3 = A(top = top)
a4 = A(top = top)

b1 = B()
b2 = B()
b3 = B()
b4 = B()

a1.addB(b1)    
a1.addB(b2)

a2.addB(b1)
a2.addB(b2)
a2.addB(b3)

a3.addB(b4)

a4.addB(b2)
a4.addB(b4)

# Slow:
top.destroySelf()

# Fast:
# Top.deleteBy(id = top.id)



The first destroy statement results in these queries:

 1/Select  :  SELECT a.id, a.top_id FROM a WHERE ((a.top_id) = (5))
 2/Query   :  DELETE FROM ab WHERE a_id=17
 1/Select  :  SELECT ab.id, ab.a_id, ab.b_id FROM ab WHERE ((ab.a_id) = (17))
 2/Query   :  DELETE FROM ab WHERE a_id=17
 1/Query   :  DELETE FROM a WHERE id = (17)
 2/Query   :  DELETE FROM ab WHERE a_id=18
 1/Select  :  SELECT ab.id, ab.a_id, ab.b_id FROM ab WHERE ((ab.a_id) = (18))
 2/Query   :  DELETE FROM ab WHERE a_id=18
 1/Query   :  DELETE FROM a WHERE id = (18)
 2/Query   :  DELETE FROM ab WHERE a_id=19
 1/Select  :  SELECT ab.id, ab.a_id, ab.b_id FROM ab WHERE ((ab.a_id) = (19))
 2/Query   :  DELETE FROM ab WHERE a_id=19
 1/Query   :  DELETE FROM a WHERE id = (19)
 2/Query   :  DELETE FROM ab WHERE a_id=20
 1/Select  :  SELECT ab.id, ab.a_id, ab.b_id FROM ab WHERE ((ab.a_id) = (20))
 2/Query   :  DELETE FROM ab WHERE a_id=20
 1/Query   :  DELETE FROM a WHERE id = (20)
 2/Query   :  DELETE FROM top WHERE id = (5)
 1/Query   :  DELETE FROM top WHERE id = 5

whereas the second destroy statement produces just

 1/Query   :  DELETE FROM top WHERE id = 4

It seems like sqlobject is iterating though all of top's siblings in order to destroy them. In case I have many of these siblings, the DB is able to perform this operations magnitudes faster than sqlobject. Is deleteBy() the preferred (the only?) way for doing just this?

Thanks,
Bernhard

___________________________________________________________________

Disclaimer:


Diese Mitteilung ist nur fuer die Empfaengerin / den Empfaenger bestimmt.

Fuer den Fall, dass sie von nichtberechtigten Personen empfangen wird, bitten wir diese hoeflich, die Mitteilung an die ZKB zurueckzusenden und anschliessend die Mitteilung mit allen Anhaengen sowie allfaellige Kopien zu vernichten bzw. zu loeschen. Der Gebrauch der Information ist verboten.


This message is intended only for the named recipient and may contain confidential or privileged information.

If you have received it in error, please advise the sender by return e-mail and delete this message and any attachments. Any unauthorised use or dissemination of this information is strictly prohibited.