This document discusses Realm, a mobile database solution that uses a column-based data structure for fast queries. It provides examples of how to query data using Realm by extending RealmObject classes, executing transactions, and using relationships, sorting, and asynchronous queries. The document also covers migrations, encryption, and an adapter for Realm.

1. Realm Java
Leonardo YongUk Kim lk@realm.io

2. Yet another
database?

4. No more SQL

5. String query = "SELECT " + Owner.NAME + ", " + Dog.NAME + ", " + City.NAME
+ " FROM " + Owner.TABLE_NAME
+ " INNER JOIN " + Dog.TABLE_NAME + " ON " + Owner.DOG_ID + " = " +
Dog.ID
+ " INNER JOIN " + City.TABLE_NAME + " ON " + Owner.CITY_ID + " = " +
City.ID
+ " WHERE " + Owner.NAME = "'" + escape(queryName) + "'";

6. Use cases

9. Fastest

14. Why is it so fast?

21. Traditional data structure
Column-based data structure
• Padding bits are not needed anymore.
• Queries for columns help the cache hit rate.
• Boolean type fields are put into integers field.
• Other fields are packaged as 1, 2, 4, 8, 16, 32, 64bits.
• More space efficient than SQLite (~50%)

22. How to use?

23. Extend RealmObject class

24. Create a standalone object, and then copy it to Realm

25. Instantiate through the Realm directly

26. Use realm.executeTransaction() method

27. Asynchronous transactions

28. Logical operators

29. Sorting

30. Chaining

31. Aggregation

32. Iteration

33. Deletion

34. Async queries

35. Async queries (cont.)

36. Relationships (Many-To-One)

37. Relationships (Many-To-One)

38. Link queries
RealmResults<Contact> contacts =
realm.where(Contact.class).equalTo("emails.active", true).findAll();

39. Migrations

40. Migrations (cont.)

41. Encryption

42. Adapter

43. Q&A kr@realm.io