You'll learn how Galera integrates with MySQL 5.6 and Global Transaction IDs to enable cross-datacenter and cloud replication over high latency networks. The benefits are clear; a globally distributed MySQL setup across regions to deliver Severalnines availability and real-time responsiveness. Galera Cluster for MySQL is a true multi-master MySQL replication plugin, and has been proven in mission-critical infrastructures of companies like Ping Identity, AVG Technologies, KPN and HP Cloud DNS. In this webcast you¹ll learn about the following Galera Cluster capabilities, including the latest innovations in the new 3.0 release: Galera Cluster features and benefits Support for MySQL 5.6 Integration with MySQL Global Transaction Identifiers Mixing Galera synchronous replication and asynchronous MySQL replication Deploying in WAN and Cloud environments Handling high-latency networks Management of Galera

1. Galera
Cluster
Release 3.0 New Features
Seppo Jaakola
Codership

2. Agenda
●
Galera Cluster Release History
●
Release 3.0 New Features
●
●
●
●
WAN Replication
5.6 GTID Support
MySQL Replication Support
Galera Project
www.codership.com
2

3. 20 Galera Replication Plugin Releases since 2009
www.codership.com
3

4. 35 Galera Cluster for MySQL Releases since 2009
www.codership.com
4

5. Galera Cluster 2.0
read & write
read & write
read & write
Read & write access to any node
Client can connect to any node
There can be several nodes
MySQL
MySQL
MySQL
Galera Replication
Replication is synchronous
www.codership.com
5

6. Galera Cluster 2.0
read & write
read & write
read & write
Multi-master cluster looks
like one big database with
multiple entry points
a
MySQL
www.codership.com
6

7. Galera Cluster 2.0
➢
Synchronous multi-master cluster
➢ no data loss
➢ no slave lag
➢ no slave failover
➢
For MySQL/InnoDB
➢
3 or more nodes needed for HA
➢
No single point of failure
www.codership.com
7

8. Galera Cluster 2.0
➢
Good Performance
Optimistic concurrency control
➢ Parallel Replication
➢ Optimized Group Communication
➢
➢
99.99% transparent
➢ InnoDB look & feel
➢
Automatic node joining
➢
Works in LAN / WAN / Cloud
www.codership.com
8

9. Galera Cluster 3.0

10. Galera 3.0
Galera Cluster 3.0 in beta test cycle atm
Having focus in:
WAN replication
– Asynchronous replication topologies
–
www.codership.com
10

11. Galera 3.0
Featuring:
●
MySQL 5.6 Support
●
Optimization for WAN replication
●
●
Asynchronous replication topologies
●
●
●
Async replication can be interleaved with Galera replication
Support for MySQL 5.6 GTID
New write set key format
●
●
●
Cluster can be divided in segments based on location
Makes certification faster
A step towards huge transaction support
A number of bug fixes and minor improvements
www.codership.com
11

12. MySQL 5.6 Support

13. MySQL 5.6 Support
Galera Cluster 3.0 has support both for
MySQL 5.5 and 5.6 versions
From Galera perspective, it does not matter
much what the DBMS is like, as long as it
supports transactions.
In MySQL 5.6, interesting new features are:
–
MySQL GTID
–
InnoDB full text search
–
Overall performance improvements
www.codership.com
13

14. MySQL 5.6 Support
We will also support MariaDB 10, work is
ongoing
Percona XtraDB Cluster will also have 5.6
based version coming soon
www.codership.com
14

15. MySQL 5.6 Support
Support for MySQL 5.1 is dropped
Future releases are for MySQL 5.5 and 5.6
only
Release builds now also for FreeBSD
www.codership.com
15

16. WAN Replication

17. WAN Replication 2.0
Galera 3.0 has new replication mode, which
is optimized for WAN networks (or any
network with high latencies in general)
But, let's first take a look how Galera 2.0
replication looks between data centers
www.codership.com
17

18. WAN Replication 2.0
A-1
A-2
B-1
A-3
B-2
Data center A
●
B-3
Data center B
All point-to-point connections will be needed for replication
www.codership.com
18

19. WAN Replication 2.0
A-1
A-2
B-1
A-3
B-2
Data center A
●
B-3
Data center B
All point-to-point connections will be needed for replication
www.codership.com
19

20. WAN Replication 2.0
A-1
A-2
B-1
A-3
B-2
Data center A
●
●
B-3
Data center B
All point-to-point connections will be needed for replication
I said ALL
www.codership.com
20

21. WAN Replication 2.0
Due to using all point-to-point connections,
the transaction latency is dictated by the
longest latency in the cluster replication
mesh
Despite of this anomaly, Galera Cluster 2.0
and earlier have been widely used in WAN
environments
www.codership.com
21

22. WAN Replication 3.0
A-1
A-2
B-1
A-3
B-2
Data center A
●
●
B-3
Data center B
Replication between cluster segments go over one link only
Replication events will be distributed within each segment p2p
www.codership.com
22

23. WAN Replication 3.0
A-1
A-2
B-1
A-3
B-2
Data center A
●
●
●
B-3
Data center B
Replication between segments go over one link only
Replication events will be distributed within each segment p2p
Segment gateways can change per transaction
www.codership.com
23

24. WAN Replication 3.0
commit
A-1
B-1
WS
A-2
A-3
B-2
Data center A
B-3
Data center B
www.codership.com
24

25. WAN Replication 3.0
A-1
WS
B-1
WS
WS
A-2
A-3
B-2
Data center A
B-3
Data center B
www.codership.com
25

26. WAN Replication 3.0
A-1
WS
B-1
WS
A-2
WS
A-3
WS
B-2
Data center A
B-3
Data center B
www.codership.com
26

27. WAN Replication 3.0
Define cluster segments up front, by node
location
gmcast.segment = 1..255
www.codership.com
27

28. WAN replication
●
Works fine
●
Use higher timeouts
●
No impact on reads
●
No impact within a transaction
●
adds 100-300 ms to commit
latency
●
No major impact on tps
●
Quorum between data centers
–
3 data centers
–
Weighted quorum calculation
–
Garbd arbitrator
28

29. MySQL Replication Topologies

30. Galera + MySQL Replication
Galera Cluster can operate both as MySQL
master and MySQL slave
●
●
MySQL master fail over in Galera Cluster has
been challenging until now
MySQL Slave operation has performance
bottleneck
Galera 3.0 solves both these problems
www.codership.com
31

31. Galera as MySQL Slave
Galera Cluster can operate as MySQL slave
in two ways:
1.MySQL master is like client connection to Galera
node (version 2 and 3)
2.MySQL replication events will be delivered as
pre-ordered events interleaved in Galera
replication (new version 3 feature)
www.codership.com
33

32. Galera as MySQL Slave
MySQL
master
MySQL replication
Node 1
slave
Node 3
Node 2
a
www.codership.com
34

33. MySQL Slave through Galera Replication
MySQL replication
Slave
processing
Query
processing
Commit processing
Write set population
WS
WS
replication
WS
Certification
Commit
www.codership.com
35

34. MySQL Slave through Galera Replication
MySQL replication
Slave
processing
Query
processing
Commit processing
Write set population
WS
WS
replication
WS
Certification
Commit
www.codership.com
36

35. Async Replication Bottleneck
●
As MySQL replication events are treated as
regular client transactions, they must go
through Galera replication pipeline at commit
time
●
… and this adds some delay before commit
●
MySQL replication is single threaded
Galera node will not apply replication events as fast as native MySQL Slave
●
MySQL 5.6 “parallel replication” can help
–
But only, f you have several schemas
–
MySQL 5.7 and MariaDB 10 will have proper parallel
replication
www.codership.com
37

36. MySQL Replication Bundling
●
●
●
Replication events can be bundled to commit as
a single group
Less waiting for replication synchronization
wsrep_mysql_replication_bundle=n
–
●
Groups n mysql replication transactions in one large
transaction
Helps with the latency, you can go up to 5K
trx/sec
www.codership.com
38

37. 3.0 Pre-ordered Replication

38. Pre-ordered replication
MySQL replication
Preordered
replication
Slave
processing
Query
processing
Commit
M
replication
G
G
www.codership.com
40

39. Pre-ordered Replication
●
●
●
●
MySQL replication stream constitutes partial
order, which can be interleaved with cluster
replication
SQL slave thread broadcasts MySQL replication
events before applying them
Galera replication does not slow down SQL slave
thread
Note, we expect MySQL replication stream to be
conflict free
www.codership.com
41

40. Pre-ordered Replication
MySQL
master1
MySQL
replication
G-1
Node 2
M-5
Node1
MySQL slave
Galera
Replication
G-2
G-4
M-3
Node 3
www.codership.com
42

41. Pre-ordered Replication
●
●
Galera nodes will receive and apply MySQL
replication events in same order and interleaved
with local Galera replication events
If MySQL replication has conflicts with Galera
events, node will do emergency shutdown
●
●
A better approach for dealing with conflicts is under works
The usual multi-master conflict scenarios apply here
●
●
●
Delete conflict
Update conflict
Uniqueness conflict
www.codership.com
43

42. MySQL Replication – Multi Source
MySQL
master1
MySQL
replication
MySQL
master2
Node1
MySQL slave
Galera
Replication
Node2
MySQL slave
MySQL
replication
Node3
MySQL master
MySQL
replication
MySQL
www.codership.com
slave
44

43. MySQL Replication – Multi Source
Works with both MySQL replication
strategies
●
“Slave through Galera Replication”, provides
certification for MySQL masters
–
●
Consistency is guaranteed
“pre-ordered Replication”, is high speed but
requires consistency guarantee from application
www.codership.com
45

44. MySQL 5.6 GTID Support

45. GTID Support
MySQL 5.6 introduces global transaction
identifier (GTID), which can greatly ease up
the MySQL replication master fail over
In Galera Cluster, all nodes will generate
different binlog files
●
●
Binlog events are same and in same order, but binlog file
offsets may vary
Galera community has developed miracles to cope with this, it
is amazing what a single line of perl code can do
www.codership.com
47

46. Galera Binlogging
Node 1
Node 2
Insert into t0...
Insert into t0...
Mysqld-bin.00007
Mysqld-bin.00008
www.codership.com
48

47. GTID Support
Galera will preserve the MySQL GTID events
both in “galera replicated mysql slave” and
“pre-ordered replication” methods.
Galera nodes will generate Galera Cluster
GTID for Mysql replication. MySQL slaves
will see the Galera Cluster as one MySQL
master
Master fail over in Galera Cluster can
happen by using the GTID
www.codership.com
49

48. Galera Binlogging
Node 1
mysql-GTID-1
Insert into t0...
Mysqld-bin.00007
Node 2
mysql-GTID-1
Insert into t0...
Mysqld-bin.00008
www.codership.com
50

49. Galera Binlogging
Node 1
mysql-GTID-1
Insert into t0...
Node 2
mysql-GTID-1
Insert into t0...
mysql-GTID-1
mysql-GTID-1
Mysqld-bin.00007
Mysqld-bin.00008
GTID for
Cluster
events
www.codership.com
51

50. Certification Key Optimization

51. Certification Keys
Write set contains references for all affected
primary, unique and foreign keys
These affected keys are also stored in
certification index maintained in each node
to find out possible multi-master conflicts
www.codership.com
53

52. Certification Key
Keys
Write
set
Write
set
Binlog
events
Certification index
Galera 2.0
Keys
Binlog
events
Certification index
Galera 3.0
www.codership.com
54

53. Certification Keys
Galera 3.0 has refactored these key
representations so that same compact
format can be used in write set and
certification index
Memory footprint is minimal for each key
and fixed length
Certification check runs faster on the new
format
More and larger transactions can run
simultaneously without memory issues
www.codership.com
55

54. Huge Transaction Support
Key format refactoring is one step forward
in huge transaction support
However, more work remains for achieving
that:
●
We still populate the full write set in main
memory, so each single transaction must fit in
the available RAM
LOAD DATA transaction can be split in a
series of 10K row transactions
wsrep_load_data_splitting = ON | OFF
www.codership.com
56

55. Galera Project

56. Galera Project
●
Galera Cluster for MySQL
●
●
●
●
●
6 years development
based on MySQL server community edition
Fully open source
Active community
~3 releases per year
●
●
●
Latest GA release 2.7
Major release 3.0 beta
3.* and 4.0 series in the works
www.codership.com
58

57. Galera Clusters
MySQL
Community edition
www.codership.com
59

58. Galera Clusters
MySQL
Community edition
WSREP API
Galera Replication plugin
www.codership.com
60

59. Galera Clusters
Galera Cluster for MySQL
MySQL
Community edition
WSREP API
Galera Replication plugin
www.codership.com
61

60. Galera Clusters
Galera Cluster for MySQL
Percona
Server
fork
MySQL
Community edition
fork
MariaDB
WSREP API
Galera Replication plugin
www.codership.com
62

61. Galera Clusters
Galera Cluster for MySQL
Percona
Server
WSREP API
MySQL
MariaDB
Community edition
merge
WSREP API
merge
WSREP API
Galera Replication plugin
www.codership.com
63

62. Galera Clusters
Percona XtraDB Cluster
Galera Cluster for MySQL
Percona
Server
WSREP API
MySQL
MariaDB
Community edition
merge
WSREP API
MariaDB Galera Cluster
merge
WSREP API
Galera Replication plugin
www.codership.com
64

63. End of Part One
Please post questions in chat window