The document provides an overview of Galera 4, a replication plugin for database servers, highlighting its features such as streaming replication, new metadata tables, and improvements for handling large transactions. It details the architecture of Galera clusters, replication types, and mechanisms for cluster recovery. Additionally, it covers the agenda of a presentation on these topics at a MyDBOps meetup, along with insights into the company’s offerings in database consulting and support.

1. What’s new in Galera 4 ?
Mydbops Meetup - 4
Presented by
M.Aakash
www.mydbops.com info@mydbops.com 1

2. About me
2
Aakash Muthuramalingam
Certified MySQL 5.7 DBA, Mydbops
Interested on MySQL Optimization and High Availability systems.
Active MySQL Blogger.
LinkedIn :
https://www.linkedin.com/in/aakash-muthuramalingam-520a77129
Twitter: https://twitter.com/Aakash_07

3. About Mydbops
● Founded in 2015, HQ in Bangalore India with 150+ customer base across the globe.
● Mydbops is on Database Consulting with core specialization on MySQL and MongoDB Administration and
Support.
● We have expert team with 20+ certified DBA’s providing full time support and currently managing 300+
servers on premises and cloud.
● We help organisations to architect and scale systems in MySQL/MongoDB by implementing the advanced
technologies in industry which are completely open source.
● We are a leading solution provider in the market for all sort of cloud based database deployments and
management.
3

4. Mydbops at a GlanceHappy Customers
4

5. Agenda
● Galera Replication Overview
● Galera 4 features
● Streaming Replication
● Configuring Streaming Replication
● Rolling Upgrade
● Other features
5

6. Galera Replication Overview
6

7. Replication in MySQL
● Asynchronous Replication
● Semi-synchronous Replication
● Synchronous Replication
7

8. Asynchronous Replication
8

9. Semi Synchronous Replication
9

10. Synchronous Replication
10

11. Galera Replication Overview
● Replication Plugin for database servers
● Using the Replication API to interact with a DBMS.
● Database and Galera plugin must have the same
11

12. Galera Replication Overview
Galera Cluster Basic Architecture
12

13. Galera Replication Overview
● Read/Write to any node
● Automatic Node Provisioning
● Each node has identical data
● Synchronous Replication
● No Slave Lag
13

14. Galera Replication Overview
● Distributions:
14
Galera 3 Galera 4
MariaDB 5.5, 10.0, 10.1, 10.2 ,10.3 MariaDB 10.4
Percona XtraDB Cluster 5.5, 5.6, 5.7 Percona XtraDB Cluster 8.0 (In
Development Phase)

15. Features
15

16. Galera Features
Galera 3(Existing Features)
● Intelligent Donor Selection
● Cluster Crash Recovery
Galera 4(New Features)
● Huge Transaction Support by Streaming Replication
● New metadata tables
16

17. Existing Features
17

18. Intelligent Donor Selection
18

19. Intelligent Donor Selection
● Intelligent donor choice:
1) Provide IST
2) Within same proximity
3) wsrep_sst_donor
19

20. Cluster Crash Recovery
20

21. Cluster Crash Recovery
21

22. Cluster Crash Recovery
22

23. Cluster Crash Recovery
23

24. Cluster Crash Recovery
24

25. Cluster Crash Recovery
25

26. Cluster Crash Recovery
● If all the nodes in the cluster shutdown
1) First node should be elected
2) Manual operation needed
3) Error Prone
26

27. Cluster Crash Recovery
● Perform automatic crash recovery
● pc.recovery=on
● Nodes will maintain the information in disk (Persistent storage)
● gvwstate.dat
27

28. New Features
28

29. Streaming Replication
29

30. Streaming Replication
In Galera 3
● Currently transactions processes in master node only until commit
● For huge transactions, the size of write-set will be large
● wsrep_max_ws_size
● wsrep_max_ws_rows
● Maximum supported size is 2GB
30

31. Streaming Replication
31
T1

32. Streaming Replication
32
T1

33. Streaming Replication
33
T1

34. Streaming Replication
34
T1

35. Streaming Replication
35
T1

36. Streaming Replication
In Galera 4
● Transactions are replicated in small fragments in all the nodes during processing
● This allows nodes to process writesets greater than 2GB
● Replicated fragments hold locks in all nodes
36

37. Streaming Replication
Configuring Streaming Replication
● wsrep_trx_fragment_unit - bytes/rows/statements
● wsrep_trx_fragment_size - Threshold size
37

38. Streaming Replication
38
T1
T1(p1)
T1(p1)
T1(p1)

39. Streaming Replication
39
T1
T1(p2)
T1(p2)
T1(p2)

40. Streaming Replication
40
T1

41. Fragment Applying
41

42. Fragment Applying
42

43. Fragment Applying
43

44. Fragment Applying
44

45. Fragment Applying
45

46. Fragment Applying
46

47. Fragment Applying
47

48. New Metadata Tables
48

49. New Metadata Tables
49

50. New Metadata Tables
50

51. New Metadata Tables
51

52. New Metadata Tables
52

53. Streaming Replication Demo
53

54. Node 1 (Galera 3)
54

55. Node 2 (Galera 3)
55

56. Node 1 (Galera 4)
56

57. Node 2 (Galera 4)
57

58. Node 2 (Galera 4)
58

59. Node 2 (Galera 4)
59

60. Rolling Upgrades
60

61. Rolling Upgrades
61

62. Rolling Upgrades
62

63. Rolling Upgrades
63

64. Rolling Upgrades
64

65. Rolling Upgrades
65

66. Rolling Upgrades
66

67. Rolling Upgrades
67

68. Rolling Upgrades
68

69. Rolling Upgrades
69

70. Other Features
70

71. Other Features
● Non Blocking DDL
● Gcache Encryption
● Cluster Error Voting
71

72. Summary
● Replication in MySQL
● Galera Features
● Streaming Replication
● Rolling Upgrades
● Streaming Replication Examples
72

73. Queries?
73

74. Thank You
74