Getting into REAL(M) business by dumping SQLite

Presented this talk at DevFest Ahmedabad 2015 (#DevFestAhm). In this talk I have covered what is Realm? Why you should use Realm over SQLite and ORM with code snippets.

Transcript

1. Getting into REAL (M) business by dumping SQLite
2. Hello! I am Dhrumil Shah I work at Bugle Technologies Pvt. Ltd. & Co-organizer at GDG Ahmedabad. You can find me at: @dhuma1981 +DhrumilShah
3. “
4. Why you should dump SQLite?
5. Typical Apps Requirement Lot of Data Tables W orks Offline Persist Locally
6. Problems :( More Data More Tables
7. Duplicate Data Normalization
8. Normalization More m:n
9. More m:n
10. BoilerPlate mess ▷ 1000’s of lines of boilerplate mess ▷ Lot of string just to define a single table ▷ Tightly coupled schema ▷ RAW SQL Queries
11. Nested Queries SELECT table1.col, table3.col FROM table1 JOIN table2 ON table1.primarykey = table2.foreignkey JOIN table3 ON table2.primarykey = table3.foreignkey
12. Nested Queries String query = “select” + table1.col + ”,” + table3.col + “FROM” + table1 + “JOIN” + table2 + “ON” + table1.primarykey + “=” + table2.foreignkey + “JOIN” + table3 + “ON” + table2.primarykey + “=” + table3.foreignkey
14. Let’s abstract the problem Use ORM
15. ▷ SugarORM ▷ ORMLite ▷ CubBoard ▷ ActiveRecord ▷ Ollie ▷ DBFLow ORM Options ▷ DBQuery ▷ GreenDao ▷ EasyLiteORM ▷ RushORM ▷ SpringkilesBlack ▷ . . . .
16. ▷ Easy setup ▷ Abstract SQLite boilerplate codes ▷ No direct dealing with SQL ▷ Object Mapping ORM Good Part
17. ▷ Slow, Most ORM uses reflections, read write performance is slow ▷ Not entirely SQL free, still need to write queries for certain task ▷ And as underlying is SQLite all the issues with database scaling. ORM Bad Part
18. What is Realm? Realm is an object database designed for mobile
19. “ Zero Copy Object Store
20. Object Store A E B D C VS
21. Object Store SELECT table1.col, table3.col FROM table1 JOIN table2 ON table1.primarykey = table2. foreignkey JOIN table3 ON table2.primarykey = table3. foreignkey
22. Object Store A E B D C Realm.getA().getB().getD()
23. “ Zero Copy
24. // create Cursor in order to parse our sqlite results Cursor cursor = sqliteDB.rawQuery("SELECT bookTitle FROM " + tableName, null); // if Cursor contains results if (cursor != null) { // move cursor to first row if (cursor.moveToFirst()) { do { // Get version from Cursor String bookName = cursor.getString(cursor.getColumnIndex("bookTitle")); } while (cursor.moveToNext()); } } What is Zero Copy
25. Zero Copy Src: Building Mobile DataBase by Christian Melchior http://www.slideshare.net/ChristianMelchior/realm- building-a-mobile-database#25
26. Person person = new Person() //Standard Java Person proxyperson = realm.copyToRealm(person) //Proxy object Person proxyperson = realm.createObject(Person.class) //Proxy object //Query Results are Lazy RealmResults<Person> queryResults = realm.allObjects(Person.class) queryResult.get(0) != queryResult.get(0) //different objects queryResult.get(0).equals(queryResult.get(0)) //same data Zero Copy
27. ▷ Easy Setup ▷ Memory mapped files ▷ C++ core ▷ B+ trees ▷ Column Oriented ▷ Minimize IO overhead ▷ Cross platform ▷ Faster Read & writes ▷ Read > Writes ▷ Simple Querying interface Designed for Mobile
28. Benchmarking Benchmarking realm against other databases
29. Src: Building Mobile DataBase by Christian Melchior http://www.slideshare.net/ChristianMelchior/realm- building-a-mobile-database#25
30. Sample against 1,00,000 objects read and write
31. Let’s See some Code
32. Setup compile 'io.realm:realm-android: 0.86.1' Realm realm = Realm.getInstance(context)
33. Method and Size ▷ ~ 1750 method counts ▷ adds ~730 KB fat to apk ▷ install size less
34. Realm Objects //Standard Java POJO from RealmObject public class Person extends RealmObject { @PrimaryKey private String personName; private int personAge; ….. …... //Getters and Setters }
35. Writing Data //Standard Java extend person from RealmObject Person person = new Person() //call setter to set data …. //save data try{ realm.beginTransaction(); realm.copyToRealm(person); realm.commitTransaction(); }catch(Exception e){ realm.cancelTransaction(); // rollback data }
36. Writing Data Async Block //transaction block realm.executeTransaction(new Realm.Transaction() { @Override public void execute(Realm realm) { Person person = realm.createObject(Person.class); person.setName("John"); person.setEmail("john@corporation.com"); } });
37. ▷ Supports Primary Key ▷ Supports primitive data types like int, long, boolean etc. ▷ Supports Box types like Integer, Long, String etc. ▷ Allows null value for non primitives types ▷ Supports Indexing Realm Object
38. Query Data // Build the query looking at all users: RealmQuery<User> query = realm.where(User.class); // Add query conditions: query.equalTo("name", "John"); query.or().equalTo("name", "Peter"); // Execute the query: RealmResults<User> result1 = query.findAll(); // Or alternatively do the same all at once (the "Fluent interface"): RealmResults<User> result2 = realm.where(User.class) .equalTo("name", "John") .or() .equalTo("name", "Peter") .findAll();
39. Query Data // Queries use Builder pattern to build up the query conditions RealmResults<Dog> query = realm.where(Dog.class) .greaterThan("age", 8) .findAll(); // Queries are chainable RealmResults<Dog> allRex = query.where() .contains("name", "rex") .findAll();
40. ▷ Conditions like lessThan, greaterThan, contains, beginsWith etc ▷ Modifiers for ignoring Cases ▷ Logical Operations OR AND ▷ Sorting Ascending, Descending ▷ Chaining Queries ▷ Aggregations like SUM, MIN, MAX, AVG ▷ Synchronous, Asynchronous operations Query Data Supports
41. Relationships // Any Realm Object can be linked together public class Email extends RealmObject { private String address; private boolean active; // ... setters and getters left out } public class Contact extends RealmObject { private String name; private Email email; // ... setters and getters left out }
42. Link Queries // You can now link queries together RealmResults<Contact> contacts = realm.where(Contact. class).equalTo("emails.active", true).findAll();
43. ▷ Direct support for Json to Object store ▷ Notification for database change like CP ▷ Encryption support in built ▷ Adapters for binding data with views ▷ Cross Platform, same data can work across iOS and Android ▷ Robust 3rd parties addons Other Features
44. Limitations
45. ▷ Not Entirely NOSQL, need migration on schema Changes ▷ No support for auto incrementing primary keys ▷ Closed source code ▷ Mutable, thread-confined objects ▷ No support for realm objects across threads ▷ Slower write ▷ Increase method count and size of apk Limitations
46. Realm Browser
47. Mac App to browse data stored on realm files (there is a separate plugin for STETHO)
48. Who else is using Realm Is it production ready?
50. Thanks! Any questions? You can find me at: @dhuma1981 +DhrumilShah dhuma1981@gmail.com
51. Credits Special thanks to all the people who made and released these awesome resources for free: ▷ Realm by realm.io ▷ Christian Melchior from Realm Team ▷ Pranay Airan from GDG BlrDroid ▷ Presentation template by SlidesCarnival