Capacity of NSDictionary

[Andreas Höschler]

Hi all,

I am using a dictionary to hold business objects. As the key I use a 
class SOObjectID which basically looks as follows:

@interface SOObjectID : NSObject < NSCopying, SRArchivingProtocol >
{
   int _identifier; // entity
   int _primaryKey;
}

- (unsigned int)hash
{
   return (_primaryKey * 1000 + _identifier);
}

- (BOOL)isEqual:(id)object
{
   if (self == object) return YES;
   if ([object isKindOfClass:[SOObjectID class]])
     {
      return ([(SOObjectID *)object identifier] == _identifier && 
[(SOObjectID *)object primaryKey] == _primaryKey);
     }
   else return NO;
}

I am hitting a serious performance problem when holding many objects in 
the dictionary. Currently I am running a test with 3 GB of data loaded 
into the process (running under Solaris 10) and it's getting slow as 
hell. The machine has 16 GB of RAM so swapping is not an issue. I know 
that the above is not the cutest way to hold great chunks of data. I 
already wondered whether it would be a good idea to replace the 
NSDictionary with something that uses a binary tree to hold the data. 
However, since this is not done in a couple of minutes I would 
appreciate to find an easier solution for now. How many objects should 
a dictionary be able to handle with reasonable performance? Anything I 
could do in my SOGlobalID class to improve performance?

Thanks a lot!

Regards,

  Andreas