Core Data Performance
-
I know that this subject has been covered many times and all the
related posts are very useful. However, I was reading the
documentation recently and I'm sure that I read somewhere that there
is a way to query the Managed Object Context instead of executing a
fetch request. But since then I have not been able to find it in the
documentation again. Was I just imagining things or is there a way to
do this? Will the performance difference be vastly different?
Many thanks,
Phil. -
um, to execute a fetch request you do query the managed object
context. Can you clarify what you mean a little more?
Mike.
On 19 Feb 2008, at 22:35, Philip Bridson wrote:> I know that this subject has been covered many times and all the
> related posts are very useful. However, I was reading the
> documentation recently and I'm sure that I read somewhere that there
> is a way to query the Managed Object Context instead of executing a
> fetch request. But since then I have not been able to find it in the
> documentation again. Was I just imagining things or is there a way
> to do this? Will the performance difference be vastly different?
>
> Many thanks,
>
> Phil. -
Sure,
The article I read said something like:
"Executing a fetch request requires a round trip to the persistent
store.... you can avoid the overhead of executing the fetch request
by searching the managed object context..."
Something like that, to be honest I can't find it any where in the
documentation and I only posted because I started to think I might
have been imagining things.
Hope this helps.
Phil
On 19 Feb 2008, at 23:43, Mike Abdullah wrote:> um, to execute a fetch request you do query the managed object
> context. Can you clarify what you mean a little more?
>
> Mike.
>
> On 19 Feb 2008, at 22:35, Philip Bridson wrote:
>
>> I know that this subject has been covered many times and all the
>> related posts are very useful. However, I was reading the
>> documentation recently and I'm sure that I read somewhere that
>> there is a way to query the Managed Object Context instead of
>> executing a fetch request. But since then I have not been able to
>> find it in the documentation again. Was I just imagining things or
>> is there a way to do this? Will the performance difference be
>> vastly different?
>>
>> Many thanks,
>>
>> Phil.
> -
> "Executing a fetch request requires a round trip to the persistent
> store.... you can avoid the overhead of executing the fetch request
> by searching the managed object context..."
>
> Something like that, to be honest I can't find it any where in the
> documentation and I only posted because I started to think I might
> have been imagining things.
I'm having trouble understanding what you're asking too, but ...
are you perhaps referring to in-memory array filtering (with
predicates)? See NSArray's -filteredArrayUsingPredicate:
If you already have a fetched set of managed objects (assuming you
understand all the implications regarding faulting), you can filter
them in memory using this method.
--
I.S.
