CODEWITHSUNDEEP
iosobjective-ccore-data
Chirila Vasile
Chirila Vasile

Reputation: 359

NSFetchResultsController too slow

I am using NSFetchResultsController to receive items from database (there are 80.000 items).

This is my predicate: @"(desc CONTAINS[cd] %@)", [any text]

And for NSFetchRequest I set next properties:

request.propertiesToFetch = [NSArray arrayWithObject:[[entityDescription propertiesByName] objectForKey:@"icd"]];
request.returnsDistinctResults = YES;
[request setFetchBatchSize:100];
[request setSortDescriptors:[NSArray arrayWithObject:[[NSSortDescriptor alloc] initWithKey:@"icd" ascending:YES]]];

The idea behind this is that I want a live search (every character user writes in a textfield, the NSFetchResultsController should fetch into database again.

The problem is next: on iPad Mini, every fetch duration is between 2-3 seconds, which is very very much. I remember that I did same thing now 1 years ago, and worked faster.

Can you please give me some advice? I really don't know how to improve query.

Upvotes: 0

Views: 45

Answers (1)

Jody Hagins
Jody Hagins

Reputation: 28419

Your problem is your predicate. It causes a scan of every record to find which ones contain the desired search text. Furthermore, using [cd] makes it even slower.

This exact problem is addressed in the 2013 WWDC presentation on Core Data Performance.

Upvotes: 1

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