Iphone – Core Data vs Sqlite and performance

cocoa-touchcore-dataiphone

I am wondering if anyone has any real world numbers on performance differences between an old sqlite application which has been converted to Core Data in the 3.0 SDK.

I suspect that under the hood Core Data is just using sqlite anyways and that it add's a bit of overhead for the cost of convenience, but i thought i would ask anyways.

Best Answer

Core Data is heavily optimized with regards to caching, lazy-loading and memory management.

If you use it (with the SQLite store type), especially in conjunction with NSFetchedResultsController, you should get better performance than you could get with SQLite on your own.

Apple has worked hard to make Core Data perform well on the iPhone. My application switched from SQLite w/ FMDB to Core Data and it is now faster and more stable with less code.

Related Solutions

Iphone – Core Data Primary Key

Your options are:

Use -[NSManagedObject objectID]. Note that this ID is temporary until either the object is saved for the first time or you call -[NSManagedObjectContext obtainPermanentIDsForObjects:error:]
Use the CFUUID family of functions to generate a UUID for each object in your -awakeFromInsert method
Create your own primary key-like system that stores an integer in your model and increments it with the creation of each object

There is no good way to validate that a property is unique. The closest you'll get is to ensure it is unique at creation time, and then implement a custom setter method that stops anyone ever changing the ID.

Ios – Delete/Reset all entries in Core Data

You can still delete the file programmatically, using the NSFileManager:removeItemAtPath:: method.

NSPersistentStore *store = ...;
NSError *error;
NSURL *storeURL = store.URL;
NSPersistentStoreCoordinator *storeCoordinator = ...;
[storeCoordinator removePersistentStore:store error:&error];
[[NSFileManager defaultManager] removeItemAtPath:storeURL.path error:&error];

Then, just add the persistent store back to ensure it is recreated properly.

The programmatic way for iterating through each entity is both slower and prone to error. The use for doing it that way is if you want to delete some entities and not others. However you still need to make sure you retain referential integrity or you won't be able to persist your changes.

Just removing the store and recreating it is both fast and safe, and can certainly be done programatically at runtime.

Update for iOS5+

With the introduction of external binary storage (allowsExternalBinaryDataStorage or Store in External Record File) in iOS 5 and OS X 10.7, simply deleting files pointed by storeURLs is not enough. You'll leave the external record files behind. Since the naming scheme of these external record files is not public, I don't have a universal solution yet. – an0 May 8 '12 at 23:00

Best Answer

Related Solutions

Iphone – Core Data Primary Key

Ios – Delete/Reset all entries in Core Data

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