Hi Rene,
At 14:45 07/02/2003 +0100, Ren...@da... wrote:
>Hi Kal,
>
>I just wanted to delete some topics from a topic map with 2000 Topics in it -
>with the api function topic.destroy().
>In some cases I have to delete nearly all topics (I apply some filters on it)
>and I woundered why I had to wait more then 10 minutes.
>I took the time of a single destroy() and it was about 300 ms on a 700 Mhz
>machine...
Ouch!
Is this with the in-memory backend or one of the persistent stores ?
Without running any profiling, my guess is that this performance hit comes
because the code checks that the topic you are removing is not being used
as a topic/association/occurrence/role type or in a scope. Because that
information needs to be looked up from the indexes, you are getting hit
with the cost of the lookups. There are a number of ways this could be fixed:
1) Add a reference count to Topic objects - so a Topic can only be
destroyed if its ref count is 0
2) Consolidate all topic use information into a single index - so the cost
is only one lookup, not 5
(2) is probably easier to implement and will not involve changing the
database schema, but (1) would be more efficient. In fact, I could probably
implement (1) for the Ozone and in-memory backends and make the
implementation of the getRefCount() method on the RDBMS backend use a
query.... that would be almost the best of both worlds....
But before I get into making these changes, I would like to get a bit of
profiling on your problem. If you have time to do that for me, that would
be really helpful as I am kind of pressed for time at the moment.
Cheers,
Kal
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