CoreData fetch is way too slow
CoreData fetch is way too slow
- Subject: CoreData fetch is way too slow
- From: James Hober <email@hidden>
- Date: Tue, 5 Feb 2008 11:31:22 -0800
I have a CoreData app that has a SQLite store holding 157,273 managed
objects. Each managed object has 2 attributes, input and answer,
which are NSStrings and that's all. No other attributes. No
relationships. No fetched properties.
A simple fetch for a single managed object takes 7 seconds!
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"%K
like %@",
@"input", input]; //assume NSString *input exists
NSFetchRequest *fetchRequest = [[[NSFetchRequest alloc] init]
autorelease];
NSEntityDescription *entity = [NSEntityDescription
entityForName:@"MyEntity"
inManagedObjectContext:
[self managedObjectContext]];
[fetchRequest setEntity:entity];
[fetchRequest setPredicate:predicate];
[fetchRequest setFetchLimit:1];
NSError *error = nil;
//The following line takes 7 seconds to execute:
NSArray *results = [[self managedObjectContext]
executeFetchRequest:fetchRequest error:&error];
if ([results count]) {return [[results objectAtIndex:0]
valueForKey:@"answer"];}
return @"";
How can I speed this up?
The 157,273 inputs are unique. I believe CoreData searches them
linearly in no particular order, instead of sorting them so they can
be binary searched in the store. Is this aspect of CoreData opaque?
Is there no way to get CoreData to efficiently search on a unique
string attribute?
If my experiments with CoreData continue to prove unfruitful, I may
remain with my current implementation which uses Objective-C++ and
an STL map. I can load all the data into the map in about 3.6
seconds and then retrieval from memory is near instantaneous.
Thank you for any help speeding up this CoreData implementation or
any other suggestions.
_______________________________________________
Cocoa-dev mailing list (email@hidden)
Please do not post admin requests or moderator comments to the list.
Contact the moderators at cocoa-dev-admins(at)lists.apple.com
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden