GeeCon 2011 : NoSQL and In Memory Data Grids from a developer perspective by Cyrille Le Clerc and Michael Figuière - Xebia

1. NoSQL & DataGrids from a Developer Perspective
Cyrille Le Clerc - Michaël Figuière

2. Speaker
@cyrilleleclerc
blog.xebia.fr
Cyrille Le Clerc
Large Scale
DataGrids
Apache CXF

3. Speaker
@mfiguiere
blog.xebia.fr
Michaël Figuière Distributed
Systems
NoSQL
Search Engines

4. About NoSQL
No SQL

5. About NoSQL
Not Only
No SQL

6. About NoSQL
Not Only
No SQL
Relational

7. Once upon a time...

8. On the Web side
- Created Dynamo
Similar needs for Web giants :
- < 40 min of unavailability per year
• Huge amount of data
• High availability
• Fault tolerance
- Created BigTable & MapReduce
• Scalability on commodity - Stores every webpages of Internet
hardware

9. Amazon : the birth of Dynamo
Requires complex requests,
temporal unavailability is acceptable
Fill cart Checkout Payment Process order Prepare Send
Requires high availability,
key-value store is enough

10. On the Financial side
- Released Coherence in 2001
Needs within financial market :
- Started as a distributed cache
• Very low latency
• Rich queries & transactions
• Scalability
- Released Gigaspaces XAP in 2001
• Data consistency - Routes the request inside the data

11. Data Partitioning and Replication

12. Use Case : Train Ticketing System
With trains, stations,
seats, booking and
passengers

13. Store everything in a Mainframe !
Up to 3 To of RAM !
More than $1,000,000
IBM z11

14. Data Partitioning
Partition gamma
Small
servers
Partition beta
MainFrame
Partition alpha
Split data for scalability

15. Data Replication
Node 1
synchro
Partition alpha
Node 2
Duplicate data for
high availability and
Node 3
scalability

16. Partitioned Data Modeling

17. Partitioned Data Modeling
Seat
Booking Passenger
number
reduction name
price
Train
code
type
TrainStation
TrainStop
code
date
name
Typical relational data model

18. Partitionned Data Modeling
Partitioning ready
entities tree
e ntity
Root Seat
Booking Passenger
number
reduction name
price
Train
code
Du
type pli Refe
ca
ted renc
in e d
TrainStation ea ata
TrainStop ch
code pa
date rtit
ion
name
Find the root entity and denormalize

19. Partitionned Data Modeling
Remove unused data
Seat
Booking Passenger
number
reduction name
price
booked
Train
code
type
TrainStation
TrainStop
code
date
name

20. Partitionned Data Modeling
Sharding ready data structure
Seat
number
price
booked
Train
code
type
TrainStation
TrainStop
code
date
name

21. Consistency, Availability and Partition Tolerance

22. Data Consistency with replicas
Node 1
{ "name": "Barbie Computer",
"price": 15.50,
"tags" : [
"doll",
"barbie" Node 2
]}
write to all Node 3
Node 1
read from one Node 2
Node 3

23. Data Consistency with replicas
{ "name": "Barbie Computer", Node 1
"price": 15.50,
"tags" : [
"doll",
"barbie"
]}
Node 2
write to one
Node 3
Node 1
Node 2
read from all Node 3

24. Data Consistency with replicas
• You can adjust the balance between number of writes and number of
reads
• See Eventual Consistency

25. Data Consistency with Multiple Data Centers
{ "name": "Barbie Computer",
"price": 15.50,
"tags" : [
"doll",
"barbie"
]}
{ "name": "Barbie Computer",
"price": 15.50,
"tags" : [
West Coast "doll",
"barbie"
]}
East Coast

26. Data Consistency with Multiple Data Centers
set price to $ 20.00
{ "name": "Barbie Computer",
"price": 20.00,
"tags" : [
"doll",
"barbie"
]}
{ "name": "Barbie Computer",
"price": 15.50,
West Coast "tags" : [
"doll",
"barbie"
]}
East Coast
propagation delay !

27. Data Consistency with Multiple Data Centers
set price to $ 20.00
{ "name": "Barbie Computer",
"price": 20.00,
"tags" : [
"doll",
"barbie"
]} { "name": "Barbie Computer",
"price": 15.50,
West Coast "tags" : [
"doll",
"barbie",
“girl”
]}
East Coast
add tag “girl”
reconciliation API needed !

28. Data Consistency with Multiple Data Centers
set price to $ 20.00
{ "name": "Barbie Computer",
"price": 20.00,
"tags" : [
"doll",
"barbie"
]} { "name": "Barbie Computer",
"price": 15.50,
West Coast "tags" : [
"doll",
"barbie",
“girl”
]}
East Coast
add tag “girl”
Network partitioning

29. Data Consistency with Multiple Data Centers
London
New York
Tokyo
World wide replication
for financial market

30. CAP Theorem
Only 2 of these 3
properties can be
achieved in storage
Consistency
system
Availability
Partition
Tolerance

31. CAP Theorem
Relational DB
NoSQL DB
Consistency
Availability
Partition Impossible
Tolerance

32. Data models & APIs

33. Request Driven Data Modeling
• Relational data modeling is business driven
Adaptation to requests comes with tuning
• With partitioning, data modeling had to be adapted for requests
Because network latency matters
• NoSQL & DataGrids data modeling is request driven
Two requests may require to store data twice

34. Key-Value Store
In memory
In memory
with async
persistence
Persistent

35. Example with a user profile
johndoe User profile as byte[]
Similar to a Java
HashMap

36. Write Example with Riak
RiakClient riak = new RiakClient("http://server1:8098/riak");
RiakObject userProfileObj =
new RiakObject("bucket", "johndoe", serializer.serialize(userProfile);
riak.store(userProfileObj);
Inserts a user profile
into Riak

37. Read Example with Riak
FetchResponse response = riak.fetch("bucket", "johndoe");
if (response.hasObject()) {
userProfileObj = response.getObject();
}
Fetch a user profile using
its key in Riak

38. Column Families Store

39. Column Families Store
For each Row ID we have
a list of key-value pairs
Key-value
pairs are
sorted by keys
Relational DB Column families DB

40. Example with a shopping cart
johndoe 17:21 Iphone 17:32 DVD Player 17:44 MacBook
willsmith 6:10 Camera 8:29 Ipad
pitdavis 14:45 PlayStation 15:01 Asus EEE 15:03 Iphone

41. Write Example with Cassandra
Cluster cluster =
HFactory.getOrCreateCluster("cluster", new CassandraHostConfigurator("server1:9160"));
Keyspace keyspace = HFactory.createKeyspace("EcommerceKeyspace", cluster);
Mutator<String> mutator = HFactory.createMutator(keyspace, stringSerializer);
mutator.insert("johndoe", "ShoppingCartColumnFamily",
HFactory.createStringColumn("14:21", "Iphone"));
Inserts a column into the
ShoppingCartColumnFamily

42. Read Example with Cassandra
SliceQuery<String, String, String> query =
HFactory.createSliceQuery(keyspace,
stringSerializer, stringSerializer, stringSerializer);
query.setColumnFamily("ShoppingCartColumnFamily")
.setKey("johndoe")
.setRange("", "", false, 10);
QueryResult<ColumnSlice<String, String>> result = query.execute();
Reads a slice of 10 columns
from ShoppingCartColumnFamily

43. Document Store

44. Example with an item of a catalog
{
"name": "Iphone",
"price": 559.0,
item_1 "vendor": "Apple",
"rating": 4.6,
"tags": [ "phone", "touch" ]
}
The database is aware of
document’s fields and
can offers complex
queries

45. Write Example with MongoDB
Mongo mongo = new Mongo("mongos_1", 27017);
DB db = mongo.getDB("Ecommerce");
DBCollection catalog = db.getCollection("Catalog");
BasicDBObject doc = new BasicDBObject();
doc.put("name", "Iphone");
doc.put("price", 559.0);
catalog.insert(doc);
Inserts an item
document into MongoDB

46. Read Example with MongoDB
BasicDBObject query = new BasicDBObject();
query.put("price", new BasicDBObject("$lt", 600));
DBCursor cursor = catalog.find(query);
while(cursor.hasNext()) {
System.out.println(cursor.next());
}
Queries for all items with
a price lower than 600

47. In Memory Data Grids
eXtreme Scale

48. Example with train booking with IBM eXtremeScale
@Entity(schemaRoot=true)
public class Train { Seat
number
price
@Id
booked
String code; Train
code
@Index type
@Basic
TrainStop
String name;
date
@OneToMany(cascade=CascadeType.ALL)
List<Seat> seats = new ArrayList<Seat>();
@Version
int version;
...
} With Data Grids,
sub entities can have
cross relations

49. Write Example with IBM eXtreme Scale
eXtreme Scale provides
a JPA Style API
void persist(Train train) {
entityManager.persist(train);
}
Inserts a train into
eXtreme Scale

50. Read Example with IBM eXtreme Scale
/** Find by key */
Train findById(String id) {
return (Train) entityManager.find(Train.class, id);
}
/** Query Language */
Train findByTrain(String code) {
Query q = entityManager.createQuery("select t from Train t where t.code=:code");
q.setParameter("code", code);
return (Train) q.getSingleResult();
}
Simple and complex queries
with eXtreme Scale

51. More APIs
• Another Java EE versus Spring battle ? JSR 347 Data Grids vs. Spring Data
Unified API ontop of relational, document, column, key-value ?
Object to tuple projection API

52. Transactions

53. Transactions
• NoSQL usually means NO transactions
• Except when it means eXtreme Transactions !

54. Transactions Concurrency
Place order
231
canon-eos: 1
ipod : 1
headphone : 1
311
iphone: 1
...
ipad : 1 121
iphone: 1
264
concurrency on iphone 2
barbie : 1
iphone: 1 637
cabbage-doll: 1
12
cancel order if one product warehouse stocks
is missing

55. SQL Transactions
Place order
231
canon-eos: 1
ipod : 1 begin
headphone : 1
311
iphone: 1
...
for each
shoppingCart.product
select for update ...
121
ipad : 1
iphone: 1
update ...
264
commit
2
barbie : 1
iphone: 1
cabbage-doll: 1 637
12
warehouse stocks
lock duration = f(shoppingcart.length)
if too many locks on the rows, then lock table !

56. SQL Transactions
Place order select for update ...
231
canon-eos: 1
ipod : 1
headphone : 1
311
iphone: 1
...
ipad : 1 121
iphone: 1
264
2
barbie : 1
iphone: 1
cabbage-doll: 1 637
12
warehouse stocks
lock duration = f(shoppingcart.length)
if too many locks on the rows, then lock table !

57. SQL Transactions
Place order select for update ...
231
canon-eos: 1
ipod : 1
headphone : 1
311
iphone: 1
...
ipad : 1 121
iphone: 1
264
2
barbie : 1
iphone: 1
cabbage-doll: 1
637
12
warehouse stocks
lock duration = f(shoppingcart.length)
if too many locks on the rows, then lock table !

58. Transactions with Manual Compensation
Place order
DO
-1
if(stock - quantity > 0) {
stock = stock - quantity;
} else {
throw exception() !
231
UNDO
stock = stock + quantity;
311
canon-eos: 1 -1
DO
ipod : 1 if(stock - quantity > 0) {
headphone : 1 stock = stock - quantity;
} else {
throw exception() !
iphone: 1
... UNDO
stock = stock + quantity;
-1
121
DO
if(stock - quantity > 0) {
264
stock = stock - quantity;
} else {
throw exception() !
UNDO
stock = stock + quantity;
2
-1 DO
DO
if(stock - quantity > 0) { if(stock - quantity > 0) {
stock = stock - quantity;
} else {
throw exception() !
stock = stock - quantity; 637
} else {
UNDO
stock = stock + quantity;
throw exception() ! 12
}
warehouse stocks
UNDO
stock = stock + quantity;
code “do”, “undo” and the chain

59. Transactions with Manual Compensation
Place order
DO
-1
if(stock - quantity > 0) {
stock = stock - quantity;
} else {
throw exception() !
231
UNDO
stock = stock + quantity; 637
barbie : 1
iphone: 1 DO
if(stock - quantity > 0) {
-1 311
cabbage-doll: 1 stock = stock - quantity;
} else {
throw exception() !
UNDO
stock = stock + quantity; 0
DO
264
if(stock - quantity > 0) {
stock = stock - quantity;
-1
} else {
throw exception() !
UNDO
stock = stock + quantity; 12
121
warehouse stocks

60. Transactions with Manual Compensation
Place order
DO
-1
if(stock - quantity > 0) {
stock = stock - quantity;
} else {
throw exception() !
231
UNDO
stock = stock + quantity; 636
barbie : 1
iphone: 1 DO
if(stock - quantity > 0) {
-1 311
cabbage-doll: 1 stock = stock - quantity;
} else {
throw exception() !
UNDO
stock = stock + quantity; 0
DO
264
if(stock - quantity > 0) {
stock = stock - quantity;
-1
} else {
throw exception() !
UNDO
stock = stock + quantity; 12
121
warehouse stocks

61. Transactions with Manual Compensation
Place order
DO
-1
if(stock - quantity > 0) {
stock = stock - quantity;
} else {
throw exception() !
231
UNDO
stock = stock + quantity; 636
barbie : 1
iphone: 1 DO
if(stock - quantity > 0) {
-1 311
cabbage-doll: 1 stock = stock - quantity;
} else {
no more iphone !
throw exception() !
UNDO
stock = stock + quantity; 0
DO
264
if(stock - quantity > 0) {
stock = stock - quantity;
-1
} else {
throw exception() !
UNDO
stock = stock + quantity; 12
121
warehouse stocks

62. Transactions with Manual Compensation
Place order
DO
-1
if(stock - quantity > 0) {
stock = stock - quantity;
} else {
throw exception() !
231
UNDO
stock = stock + quantity; 636
barbie : 1
iphone: 1 -1 311
interrupted
DO
if(stock - quantity > 0) {
cabbage-doll: 1 stock = stock - quantity;
} else {
throw exception() !
UNDO
stock = stock + quantity; 0
DO
264
-1
cancelled
if(stock - quantity > 0) {
stock = stock - quantity;
} else {
throw exception() !
UNDO
stock = stock + quantity; 12
121
warehouse stocks

63. Transactions with Manual Compensation
Place order
DO
-1
if(stock - quantity > 0) {
undo
stock = stock - quantity;
} else {
throw exception() !
231
UNDO
stock = stock + quantity; 636 +1
barbie : 1 DO
iphone: 1 -1 311
interrupted
if(stock - quantity > 0) {
stock = stock - quantity;
cabbage-doll: 1 } else {
throw exception() !
UNDO
stock = stock + quantity;
0
DO
264
-1
cancelled
if(stock - quantity > 0) {
stock = stock - quantity;
} else {
throw exception() !
UNDO
stock = stock + quantity; 12
DO 121
if(stock - quantity > 0) {
stock = stock - quantity;
} else {
}
throw exception() !
warehouse stocks
UNDO
stock = stock + quantity;

64. Transactions with Manual Compensation
• Code “do” & “undo” & chain execution
• What about interrupted chain execution ? Data corruption ?

65. Transactions with Manual Compensation
• Code “do” & “undo” & chain execution
• What about interrupted chain execution ? Data corruption ?
data store managed transaction chain execution

66. Which solution to choose?

67. Key-Value Store
• Get and Set by key
Simple but enough for a lot of use cases
• Riak and Voldemort provide a great scalability
Great to persist continuously growing datasets
• Memcached and Redis offer low overhead and latency
Great for cache and live data

68. Column Families Store
• Get and Set by key of a list of columns
Makes it possible to fetch and update partial data
• Queries are simples, but columns slice fetching is possible
Great for pagination
• Data model is too low level for many complex data modeling
Should typically be used for the largest scalability needs

69. Document Store
• Schema less
Great for continuously updated schemas
• Complex queries are available
Necessary for filtering and search
• Scalability may be limited if not querying using partition key
Can be handle using multiple storage and limited queries

70. In Memory Data Grid
• Very Low Latency & eXtreme Transaction Processing (XTP)
Investment banking, booking & inventory systems
• In Memory - No Persistence
Most of the time backed with a database
• High budget and Developer skills required
Some Open Source alternatives are appearing

71. Polyglot storage for eCommerce
Products
Solr
search
Product catalog MongoDB
Application
User account and
Cassandra
Shopping cart
Warehouse
inventory Coherence

72. Why NoSQL & DataGrids matter ?
• Polyglot Storage: databases that fit the needs of every type of data
• Linear Scalability: being able to handle any further business requirements
• High Availability: multi-servers and multi-datacenters
• Elasticity: natural integration with Cloud Computing philosophy
• Some new use cases now available

73. Questions / Answers
?