Chapter 18 Group Replication Table of Contents This chapter explains MySQL Group Replication and how to install, configure and monitor groups. MySQL Group Replication enables you to create elastic, highly-available, fault-tolerant replication topologies. Groups can operate in a single-primary mode with automatic primary election, where only one server accepts updates at a time. Alternatively, groups can be deployed in multi-primary mode, where all servers can accept updates, even if they are issued concurrently. 3687 18.1 Group Replication Background .............................................................................................. 3688 18.1.1 Replication Technologies ............................................................................................ 3689 18.1.2 Group Replication Use Cases ..................................................................................... 3692 18.1.3 Multi-Primary and Single-Primary Modes ..................................................................... 3693 18.1.4 Group Replication Services ......................................................................................... 3697 18.1.5 Group Replication Plugin Architecture ......................................................................... 3700 18.2 Getting Started ...................................................................................................................... 3701 18.2.1 Deploying Group Replication in Single-Primary Mode ................................................... 3701 18.2.2 Deploying Group Replication Locally ........................................................................... 3714 18.3 Requirements and Limitations ................................................................................................ 3716 18.3.1 Group Replication Requirements ................................................................................. 3716 18.3.2 Group Replication Limitations ...................................................................................... 3718 18.4 Monitoring Group Replication ................................................................................................. 3721 18.4.1 GTIDs and Group Replication ..................................................................................... 3722 18.4.2 Group Replication Server States ................................................................................. 3722 18.4.3 The replication_group_members Table ........................................................................ 3723 18.4.4 The replication_group_member_stats Table ................................................................. 3724 18.5 Group Replication Operations ................................................................................................ 3724 18.5.1 Configuring an Online Group ...................................................................................... 3724 18.5.2 Transaction Consistency Guarantees .......................................................................... 3729 18.5.3 Distributed Recovery .................................................................................................. 3736 18.5.4 Network Partitioning ................................................................................................... 3751 18.5.5 Support For IPv6 And For Mixed IPv6 And IPv4 Groups ............................................... 3756 18.5.6 Using MySQL Enterprise Backup with Group Replication .............................................. 3758 18.6 Group Replication Security .................................................................................................... 3764 18.6.1 Group Replication IP Address Permissions .................................................................. 3765 18.6.2 Securing Group Communication Connections with Secure Socket Layer (SSL) .............. 3767 18.6.3 Securing Distributed Recovery Connections ................................................................. 3769 18.7 Group Replication Performance ............................................................................................. 3773 18.7.1 Fine Tuning the Group Communication Thread ............................................................ 3773 18.7.2 Flow Control .............................................................................................................. 3773 18.7.3 Message Compression ............................................................................................... 3775 18.7.4 Message Fragmentation ............................................................................................. 3777 18.7.5 XCom Cache Management ......................................................................................... 3778 18.7.6 Responses to Failure Detection and Network Partitioning ............................................. 3780 18.8 Upgrading Group Replication ................................................................................................. 3786 18.8.1 Combining Different Member Versions in a Group ........................................................ 3787 18.8.2 Group Replication Offline Upgrade .............................................................................. 3789 18.8.3 Group Replication Online Upgrade .............................................................................. 3789 18.9 Group Replication System Variables ...................................................................................... 3793 18.10 Frequently Asked Questions ................................................................................................ 3834