Empowering Big Datawith Cassandra

Empowering Big Datawith Cassandra

./me

> Renato Carelli- DevOps + Infra @ Big Data- Hardening Enthusiast- Cloud evangelist- Bitcoin speculator

./intro

./intro/CAP

Consistency

Availability Partitiontolerance

CA CP

AP

N/A

./intro/RDBMS

Data

Performance

Com

plex

ityCo

stsMana

g. ti

me

Issue

s

./intro/NoSQL

Unstructured(not really a DB) Key Value Column Graph Document

General file storageText filesLog files

Complex modelsFlexible business logicSemi-structured dataHigh volumes

OLAPAnalyticsNOT FOR UPDATES

Relations between entities (social graphs)

Agile developmentFlexible data-modelsToo many types. Eg: Corporate areas

Data Store BigQueryGFS BigTableCloudStore

./intro/BigData

./intro/specs

./intro/history

BigTable (2006) Dynamo (2007)

Open Source(2008)

{data modeling} {design}

./intro/version_historyju

l/08

apr/1

0

jul/0

9

jan/

11ju

n/11

oct/1

1

(0.1) (0.3) (0.6) (0.7)(0.8)(1.0)

apr/1

2

(1.1) (1.2)

jan/

13

sept

/13

(2.0)

sept

/14

(2.1)

sept/15 (3.0.0-rc1)

./infra

./infra/features

N1

N2N4

N3

> Masterless

> Distributed

> Decentralized [p2p]

> Elastically Scalable

> Highly Available

> Fault-Tolerant

> Tuneable Consistent

./infra/benchmark

Nodes

Ops

/sec

./infra/benchmark

./infra/references

N1 C* Node

Connection Failed

Connection Established

Updated Data

Outdated Data

ACK

Slow Connection Established

./infra/token

Murmur3Partitioner:

-2^63 to +2^63 -1

token(‘Globant’) = -6148914691517517206

./infra/token

DemoPartitioner:

1 to 100

token(‘Globant’) = 68

./infra/token_ring

Node 1 Node 2

Node 3 Node 4

./infra/token_ring

Node 1 Node 2

Node 3 Node 4

1 - 25 26 - 50

51 - 75 76 - 100

‘Glob’ = 17

‘ant’ = 94

‘Globant’ = 68

~/Images/pic.png = 69

~/media/movie.mkv = 34

./infra/token_ring/replication

Node 1 Node 2

Node 3 Node 4

1 - 25 26 - 50

51 - 75 76 - 100

‘Glob’ = 17

RF = 3

./infra/token_ring/vnodes

What about virtual nodes?

C* 1.2

./infra/coordinator

N1

N2N4

N3

./infra/coordinator

N1

N2N4

N3> readRF = 3CL = TWO

./infra/coordinator

N1

N2N4

N3> readRF = 3CL = TWO

./infra/coordinator

N1

N2N4

N3

Coordinator

> readRF = 3CL = TWO

./infra/coordinator

N1

N2N4

N3

Coordinator

> readRF = 3CL = TWO

./infra/coordinator

N1

N2N4

N3

Coordinator

> readRF = 3CL = TWO

./infra/coordinator

N1

N2N4

N3

Coordinator

> readRF = 3CL = TWO

./infra/coordinator

N1

N2N4

N3

Coordinator

> readRF = 3CL = TWO

./infra/coordinator

N1

N2N4

N3

Coordinator

> readRF = 3CL = TWO

./infra/replication

How many copies of each piece of data (partition) do we want in the system?

./infra/replication

> Replication Factor> Replication Strategy

Keyspace-based!

./infra/replication

N1

N2N4

N3RF = 3

./infra/replication

CREATE KEYSPACE Globant WITH REPLICATION = { 'class' : 'SimpleStrategy', 'replication_factor' : 3 };

./infra/replicationN1

N2N3

N4

R1

R2

Data Center - East

N1

N2N3

N4

R1

R2

Data Center - West

RF = {‘w’:3, ‘e’:2}

./infra/replication

CREATE KEYSPACE Globant WITH REPLICATION = { 'class' : 'NetworkTopologyStrategy', 'w' : 3, 'e' : 2};

./infra/consistency_level

How many replicas/nodes (based in RF) must respond to declare success?

./infra/consistency_level

Query-based!

./infra/consistency_level

N1

N2N4

N3

> writeCL = QUORUM

CL = { ANY, ONE, TWO, THREE, QUORUM, LOCAL_ONE, LOCAL_QUORUM, EACH_QUORUM, ALL }

./infra/consistency_level

N1

N2N4

N3

> readCL = ALL

CL = { ANY, ONE, TWO, THREE, QUORUM, LOCAL_ONE, LOCAL_QUORUM, EACH_QUORUM, ALL }

./infra/consistency_level

N1

N2N4

N3

> readCL = QUORUM

CL = { ANY, ONE, TWO, THREE, QUORUM, LOCAL_ONE, LOCAL_QUORUM, EACH_QUORUM, ALL }

./infra/consistency_level

Latest timestamp wins!

./infra/consistency_level/immediate

{ R + W > RF }

./infra/consistency_level/immediate

+Reads > Write CL: ALL> Read CL: ONE

./infra/consistency_level/immediate

N1

N2N4

N3

RF = 3

> writeCL = ALL

./infra/consistency_level/immediate

N1

N2N4

N3

RF = 3

> writeCL = ALL

> readCL = ONE

./infra/consistency_level/immediate

N1

N2N4

N3

RF = 3

> writeCL = ALL

> readCL = ONE

./infra/consistency_level/immediate

N1

N2N4

N3

RF = 3

> writeCL = ALL

> readCL = ONE

./infra/consistency_level/immediate

{ R + W > RF }

./infra/consistency_level/immediate

{ 1 + 3 > 3 }

./infra/consistency_level/immediate

+Writes> Write CL: ONE> Read CL: ALL

./infra/consistency_level/immediate

N1

N2N4

N3

RF = 3

> writeCL = ONE

./infra/consistency_level/immediate

N1

N2N4

N3

RF = 3

> writeCL = ONE

> readCL = ALL

./infra/consistency_level/immediate

N1

N2N4

N3

RF = 3

> writeCL = ONE

> readCL = ALL

./infra/consistency_level/immediate

N1

N2N4

N3

RF = 3

> writeCL = ONE

> readCL = ALL

./infra/consistency_level/immediate

{ R + W > RF }

./infra/consistency_level/immediate

{ 3 + 1 > 3 }

./infra/consistency_level/immediate

Balanced> Write CL: QUORUM> Read CL: QUORUM

./infra/consistency_level/immediate

N1

N2N4

N3

RF = 3

> writeCL = QUORUM

./infra/consistency_level/immediate

N1

N2N4

N3

RF = 3

> writeCL = QUORUM

> readCL = QUORUM

./infra/consistency_level/immediate

N1

N2N4

N3

RF = 3

> writeCL = QUORUM

> readCL = QUORUM

./infra/consistency_level/immediate

N1

N2N4

N3

RF = 3

> writeCL = QUORUM

> readCL = QUORUM

./infra/consistency_level/immediate

{ R + W > RF }

./infra/consistency_level/immediate

{ 2 + 2 > 3 }

./infra/read_repair

> Query ALL replicas when reading- Data from one.- Checksum + Timestamp from others.

./infra/read_repair

> If there is a mismatch:- Pull all data and merge- Write back to out of sync replicas

./infra/read_repair

Table-based!

./infra/read_repair

N1

N2N4

N3

DATA

SUM

SUM

./infra/read_repair

N1

N2N4

N3

DATA

SUM

SUM

./infra/read_repair

N1

N2N4

N3

./infra/read_repair

ALTER TABLE Globant.foobar WITH read_repair_chance = 0.2;

./infra/read_repair

> Weak Consistencyreturn results + repair

> Strong Consistencyrepair + return results

./infra/hinted_handoff

> Recovery mechanism- Stored @ Coordinator‘s system.hints- 3hs default TTL- DataCenter-based!

./infra/nodetool

$ nodetool repair> Recovering a failed node> Infreq read data (read repair chance)> Tombstone gc period (gc_grace_seconds)

./internals

./internals/write_path

Npartition key 3 n: SasoConf city: cur year: 3partition key 2 n: EkoParty city: caba year: 11partition key 1 n: pwnConf city: mdq year: 2

MEMORY

STORAGE

Memtable (1 table)

CommitLog

SSTables

... ... ... ...

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... ... ... ...

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... ... ... ...

C

./internals/write_path

N

MEMORY

STORAGE

Memtable (1 table)

CommitLog

SSTables

... ... ... ...

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... ... ... ...

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... ... ... ...

... ... ... ...

C

(Flush)

... ... ... ...

... ... ... ...

... ... ... ...

partition key 3 n: SasoConf city: cur year: 3partition key 2 n: EkoParty city: caba year: 11partition key 1 n: pwnConf city: mdq year: 2

./internals/write_path

N

MEMORY

STORAGE

Memtable (1 table)

CommitLog

SSTables

... ... ... ...

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... ... ... ...

C

... ... ... ...

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partition key 3 n: SasoConf city: cur year: 3partition key 2 n: EkoParty city: caba year: 11partition key 1 n: pwnConf city: mdq year: 2

Compaction

... ... ... ...

... ... ... ...

... ... ... ...

./internals/write_path

N

MEMORY

STORAGE

Memtable (1 table)

CommitLog

SSTables

C

... ... ... ...

... ... ... ...

... ... ... ...

... ... ... ...

... ... ... ...

... ... ... ...

... ... ... ...

... ... ... ...

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Compaction

... ... ... ...

... ... ... ...

... ... ... ...

APPEND ONLY

APPEND ONLY

IMMUTA

BLE

./hands-on

./hands-on/stress

> 1.3M writes/sec (1.3 write/µs)

> 160K reads/sec (160 reads/ms)

> Collisions?

./hands-on/stress

Custom Apps

./me/contact

> Renato Carelli- mailto: renato.carelli@globant.com- mailto: renato@carelli.com.ar- telegram: @renato

We are hiring DevOps!> mailto: solange.domijan@globant.com

Thanks!