Framgia Presentation: No-sql for Android with Realm

1. 1
X y
- Queries too slow
- Schemas change
- Complex relationships
- 3NF, BCNF…
- Nest SELECT, JOIN
- 1-n, 1-1, n-n
- Migration
- Synchonize
- Huge records
- …
SQLite problems

2. REALM
khacpv@gmail.com
15/05/2016
no-sqlite for mobile

3. Who am I?
3

4. Realm is
SQL
SELECT user.name, user.email
FROM user
INNER JOIN shop ON user.id = shop.userid
INNER JOIN city ON user.cityid = city.id
WHERE user.name = 'the flash'
No-SQL
Realm.getA().getC().getF();
A
B C
D E F
G
X
Z
y
4

5. Realm is
SQLite
SELECT user.name, user.email
FROM user
INNER JOIN shop ON user.id = shop.userid
INNER JOIN city ON user.cityid = city.id
WHERE user.name = 'khac'
No-SQLite
Realm.getA().getC().getF();
A
B C
D E F
G
X
Z
y
5

6. YOUR
logo?
6

7. How: fastest?
7

8. Galaxy S4
8

9. Zenfone 5
9

10. Why: fastest?
10

11. Speed force
• Memory-mapped files
• C++ core
• B+ trees
• Column-oriented
• Bit-packing
Minimize I/O overhead
Cross-platform
Faster reads and writes
Queries > writes (no-sql)
Smaller file size
11

12. benchmark vs SQLite
http://static.realm.io/downloads/java/android-benchmark.zip 12

13. Architecture
Realm Object Store API
Realm Internal API
JNI
Realm Core
13

14. Method count
• Realm: ~1750
• Model class: +2x no. of fields
• Proxy class: + 2x no. of fields + 11
• Total: "it depends" (~2000)
Picasso: ~600
GSON: ~950
RxJava: ~3500
Retrofit: ~494
Support Lib: ~12300
OrmLite: ~2400
14

15. How: code?
15

16. get Realm
16
web:
version:
support:
contributors:
last release:
https://realm.io
0.90.1
xamarin, java, obj-c, swift, react-native
52+ (java)
7 days ago (13/05/2016)
classpath "io.realm:realm-gradle-plugin:0.90.1"
apply plugin: 'realm-android'
ProGuard!

17. Realtime
17
update realtime

18. Types fields
18
@Required
@Ignore
@RealmClass
@Index
@PrimaryKey
boolean
byte, short,int,long -> long
float
double
String
Date
byte[]
final
transient
volatile

19. Relationships
19
n…1
n…n

20. Queries
20
• equalTo
• greaterThan
• between
• contains
• beginWith
• beginGroup
• or
• not
• isEmpty
• distinct
• sum/ count
• min/ max/ average
• findAll/ findFirst
• sort
• …

21. Insert / Update
21

22. Delete
22

23. Configuration
23
1. Encrypt with key (AES-256)
2. Migration strategy
3. In memory mode
4. Default instance
5. isAutoRefresh() & waitForChange()
6. Create from JSON
https://nelenkov.blogspot.dk/2012/05/storing-application-secrets-in-androids.html
https://developer.android.com/training/articles/keystore.html

24. Thread
Realm
Realm
object
Realm
Results
Threads
24
RealmObject
A B C
Not yet Polymorphism

25. Debug
25
Crashlytics

26. Limitations
26
1. Class names: <= 57 letters*
2. Field names: <= 63 letters
3. Nest transactions -> not supported!
4. String & byte[] < 16Mb
*Realm auto append class_ at begin of class name

27. References
• https://realm.io/news/introducing-realm
• https://realm.io/users/chatwork
• https://github.com/realm
• http://www.slideshare.net/ChristianMelchior/realm-building-a-
mobile-database
• http://www.slideshare.net/dalinaum/realm-java
• https://en.wikipedia.org/wiki/Zero-copy
• https://en.wikipedia.org/wiki/Data_structure_alignment
27

28. Q & A
28

29. • Why do you choose Realm?
• Faster 5~10 times, especialy in write data
• Combine with ActiveAndroid
• Which data should be stored in Realm?
• The data need to be writen many times, ex: total
chats.
• Should remove ActiveAndroid to only play with Realm.
• Yes, it’s doesn’t complicated but ActiveAndroid has
value too.
• Easy to synchronize with data from server
• Yes, no problem
• Use for both Android & Ios?
• Yes
29
ChatWork
Ryutaro Miyashita
https://realm.io/users/chatwork/

30. 30
Appendix

31. B+ Tree
31https://en.wikipedia.org/wiki/B%2B_tree
The primary value of a B+ tree is in storing data for
efficient retrieval in a block-oriented storage context in
particular, filesystems. (NTFS, EXT4, SQLite, Oracle …

32. Column Oriented
32http://arxiv.org/pdf/1105.4252.pdf

33. Memory-mapped
33
Memory-mapped I/O uses the same address bus to
address both memory and I/O devices
CPU
RAM
Hard Disk
I/O
https://en.wikipedia.org/wiki/Memory-mapped_file

34. http://www.slideshare.net/jpountz/how-does-lucene-store-your-data
http://lemire.me/blog/2012/03/06/how-fast-is-bit-packing/
Bit-packing
34
• Efficient technique to store blocks of small ints
• Supports random access
• Special case: bits per value = 1 is a bit set
• Say you want to store
• 5 30 1 1 10 12
• Raw data: 6 * 32 = 192 bits
• Packed : 6 * 5 = 30 bits (84% size reduction!)
0000 0000 0000 0000 0000 0000 0000 0101 = 5
0000 0000 0000 0000 0000 0000 0001 1110 = 30
0000 0000 0000 0000 0000 0000 0000 0001 = 1
0000 0000 0000 0000 0000 0000 0000 0001 = 1
0000 0000 0000 0000 0000 0000 0000 1010 = 10
0000 0000 0000 0000 0000 0000 0000 1100 = 12