Beyond SQLite & Core Data

NoSQL for Mobile

Sam Ritchie

App Data Storage

iOS Data Storage

0%

5%

10%

15%

20%

Core Data SQLite FMDB

Android Data Storage

0%

5%

10%

15%

20%

SQLite ormlite greenDAO

So What?

Logical model

Arbitrary queries

Concurrency

Tool support

Existing skills

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Replication

Full Text indexing

Spatial indexing

Schema upgrades

Object-Relational impedance

Relational DatabasesDatabases

NoSQL

Order

Order

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Customer

Customer

Customer

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Product

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Order

Customer

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Product

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Order

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Customer

Customer

Customer

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Product

Product

Product

Order

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Order

Customer

Customer

Customer

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Product

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OrderOrder

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Order +

Order

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Customer

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ProductProduct

Customer

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Options?

The File System

YapDatabase

Benchmarks

{ title : …, body : …, createdDate : …, ownerId : “users/1234”, ownerDisplayName : “Sam”, … answers : [ { score : …, body : …, ownerId : “users/4567”, ownerDisplayName : “Jon Skeet”, comments : [] }], comments : [ { score : …, text : …, ownerId : “users/1234”, ownerDisplayName : “Sam” }], tags : [ “objective-c”, “iOS” ], duplicates : [ “questions/456” ], related : [] }

questions/123 users/1234{ displayName : “Sam” reputation : 1337, profileImageURL : …, websiteURL : …, age : …, location : …, creationDate : …, lastAccessDate : … }

Fetch Tag Counts Full Text Search LOC

Core Data CouchBase Lite YapDatabase LevelDB

Awesome

Crap

Cost of Abstraction

CBLQuery *query = [[self.database viewNamed:@"tags"] createQuery]; query.groupLevel = 1; for (CBLQueryRow *row in [query run:NULL]) NSLog(@"%@ (%@)", row.key, row.value);

Couchbase Lite

__block NSString *currentTag = nil; __block int count = 0; [database enumerateKeysWithPrefix:@"i/tags/" block:^(NSString *key, BOOL *stop) { NSString *tag = [[key stringByDeletingLastPathComponent] stringByReplacingOccurrencesOfString:@"i/tags/" withString:@""]; if (!currentTag || ![currentTag isEqualToString:tag]) { NSLog(@"%@ (%d)", currentTag, count); count = 0; currentTag = tag; } count++; }]; NSLog(@"%@ (%d)", currentTag, count);

LevelDB

Cost of Abstraction

select name, count(1) from Tags group by name

NSFetchRequest* fetch = [NSFetchRequest fetchRequestWithEntityName:@"Tag"]; NSEntityDescription* entity = [NSEntityDescription entityForName:@"Tag" inManagedObjectContext:self.context]; NSAttributeDescription* nameDesc = [entity.attributesByName objectForKey:@"name"]; NSExpression *keyPathExpression = [NSExpression expressionForKeyPath: @"name"]; NSExpression *countExpression = [NSExpression expressionForFunction: @"count:" arguments: [NSArray arrayWithObject:keyPathExpression]]; NSExpressionDescription *expressionDescription = [[NSExpressionDescription alloc] init]; [expressionDescription setName: @"count"]; [expressionDescription setExpression: countExpression]; [expressionDescription setExpressionResultType: NSInteger32AttributeType]; [fetch setPropertiesToFetch:[NSArray arrayWithObjects:nameDesc, expressionDescription, nil]]; [fetch setPropertiesToGroupBy:[NSArray arrayWithObject:nameDesc]]; [fetch setResultType:NSDictionaryResultType]; NSError* error = nil; NSArray *results = [self.context executeFetchRequest:fetch error:&error]; for (NSDictionary *result in results) NSLog(@"%@ (%@)", result[@"name"], result[@"count"]);

Core Data

Live Coding Demo

Questions?

sam.ritchie@lateral.com.au