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MySQL 5.7 Reference Manual  /  Group Replication  /  Group Replication System Variables

18.6 Group Replication System Variables

These are the system variables that are specific to the Group Replication plugin. Every configuration option is prefixed with "group_replication".

Important

Although most variables are described as dynamic and can be changed while the server is running, most changes only take effect upon restarting the Group Replication plugin. Variables which can be changed without requiring a restart of the plugin are specifically noted as such in this section.

  • group_replication_group_name

    Introduced5.7.17
    Command-Line Format--group-replication-group-name=value
    System VariableNamegroup_replication_group_name
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypestring

    The name of the group which this server instance belongs to. Must be a valid UUID.

  • group_replication_start_on_boot

    Introduced5.7.17
    Command-Line Format--group-replication-start-on-boot=value
    System VariableNamegroup_replication_start_on_boot
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeboolean
    DefaultON

    Whether the server should start Group Replication or not during server start.

  • group_replication_local_address

    Introduced5.7.17
    Command-Line Format--group-replication-local-address=value
    System VariableNamegroup_replication_local_address
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypestring

    The local address as a host:port formatted string.

  • group_replication_group_seeds

    Introduced5.7.17
    Command-Line Format--group-replication-group-seeds=value
    System VariableNamegroup_replication_group_seeds
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypestring

    A list of peer addresses as a comma separated list such as host1:port1,host2:port2. Each address is validated when starting Group Replication and the list must contain at least one valid address. Any invalid host names could cause START GROUP_REPLICATION to fail.

  • group_replication_force_members

    Introduced5.7.17
    Command-Line Format--group-replication-force-members=value
    System VariableNamegroup_replication_force_members
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypestring

    A list of peer addresses as a comma separated list such as host1:port1,host2:port2. This option is used to force a new group membership, in which the excluded members do not receive a new view and are blocked. You need to manually kill the excluded servers. Any invalid host names in the list could cause subsequent START GROUP_REPLICATION statements to fail because they could block group membership.

  • group_replication_bootstrap_group

    Introduced5.7.17
    Command-Line Format--group-replication-bootstrap-group=value
    System VariableNamegroup_replication_bootstrap_group
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeboolean
    DefaultOFF

    Configure this server to bootstrap the group. This option must only be set on one server and only when starting the group for the first time or restarting the entire group. After the group has been bootstrapped, set this option to OFF. It should be set to OFF both dynamically and in the configuration files. Starting two servers or restarting one server with this option set while the group is running may lead to an artificial split brain situation, where two independent groups with the same name are bootstrapped.

  • group_replication_poll_spin_loops

    Introduced5.7.17
    Command-Line Format--group-replication-poll-spin-loops=value
    System VariableNamegroup_replication_poll_spin_loops
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted Values (32-bit platforms)Typeinteger
    Default0
    Min Value0
    Max Value4294967295
    Permitted Values (64-bit platforms)Typeinteger
    Default0
    Min Value0
    Max Value18446744073709547520

    The number of times the group communication thread waits for the communication engine mutex to be released before the thread waits for more incoming network messages.

  • group_replication_recovery_retry_count

    Introduced5.7.17
    Command-Line Format--group-replication-recovery-retry-count=value
    System VariableNamegroup_replication_recovery_retry_count
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeinteger
    Default10
    Min Value0
    Max Value31536000

    The number of times that the member that is joining tries to connect to the available donors before giving up.

  • group_replication_recovery_reconnect_interval

    Introduced5.7.17
    Command-Line Format--group-replication-recovery-reconnect-interval=value
    System VariableNamegroup_replication_recovery_reconnect_interval
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeinteger
    Default60
    Min Value0
    Max Value0

    The sleep time, in seconds, between reconnection attempts when no donor was found in the group.

  • group_replication_recovery_use_ssl

    Introduced5.7.17
    Command-Line Format--group-replication-recovery-use-ssl=value
    System VariableNamegroup_replication_recovery_use_ssl
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeboolean
    DefaultOFF

    Whether Group Replication recovery connection should use SSL or not.

  • group_replication_recovery_ssl_ca

    Introduced5.7.17
    Command-Line Format--group-replication-recovery-ssl-ca=value
    System VariableNamegroup_replication_recovery_ssl_ca
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypestring

    The path to a file that contains a list of trusted SSL certificate authorities.

  • group_replication_recovery_ssl_capath

    Introduced5.7.17
    Command-Line Format--group-replication-recovery-ssl-capath=value
    System VariableNamegroup_replication_recovery_ssl_capath
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypestring

    The path to a directory that contains trusted SSL certificate authority certificates.

  • group_replication_recovery_ssl_cert

    Introduced5.7.17
    Command-Line Format--group-replication-recovery-ssl-cert=value
    System VariableNamegroup_replication_recovery_ssl_cert
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypestring

    The name of the SSL certificate file to use for establishing a secure connection.

  • group_replication_recovery_ssl_key

    Introduced5.7.17
    Command-Line Format--group-replication-recovery-ssl-key=value
    System VariableNamegroup_replication_recovery_ssl_key
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypestring

    The name of the SSL key file to use for establishing a secure connection.

  • group_replication_recovery_ssl_cipher

    Introduced5.7.17
    Command-Line Format--group-replication-recovery-ssl-cipher=value
    System VariableNamegroup_replication_recovery_ssl_cipher
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypestring

    A list of permissible ciphers to use for SSL encryption.

  • group_replication_recovery_ssl_crl

    Introduced5.7.17
    Command-Line Format--group-replication-recovery-ssl-crl=value
    System VariableNamegroup_replication_recovery_ssl_crl
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypestring

    The path to a directory that contains files containing certificate revocation lists.

  • group_replication_recovery_ssl_crlpath

    Introduced5.7.17
    Command-Line Format--group-replication-recovery-ssl-crlpath=value
    System VariableNamegroup_replication_recovery_ssl_crlpath
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypestring

    The path to a directory that contains files containing certificate revocation lists.

  • group_replication_recovery_ssl_verify_server_cert

    Introduced5.7.17
    Command-Line Format--group-replication-recovery-ssl-verify-server-cert=value
    System VariableNamegroup_replication_recovery_ssl_verify_server_cert
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeboolean
    DefaultOFF

    Make the recovery process check the server's Common Name value in the donor sent certificate.

  • group_replication_recovery_complete_at

    Introduced5.7.17
    Command-Line Format--group-replication-recovery-complete-at=value
    System VariableNamegroup_replication_recovery_complete_at
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeenumeration
    DefaultTRANSACTIONS_APPLIED
    Valid ValuesTRANSACTIONS_CERTIFIED
    TRANSACTIONS_APPLIED

    Recovery policies when handling cached transactions after state transfer. This option specifies whether a member is marked online after it has received all transactions that it missed before it joined the group (TRANSACTIONS_CERTIFIED) or after it has received and applied them (TRANSACTIONS_APPLIED).

  • group_replication_components_stop_timeout

    Introduced5.7.17
    Command-Line Format--group-replication-components-stop-timeout=value
    System VariableNamegroup_replication_components_stop_timeout
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeinteger
    Default31536000

    Timeout, in seconds, that Group Replication waits for each of the components when shutting down.

  • group_replication_allow_local_lower_version_join

    Introduced5.7.17
    Command-Line Format--group-replication-allow-local-lower-version-join=value
    System VariableNamegroup_replication_allow_local_lower_version_join
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeboolean
    DefaultOFF

    Allow the current server to join the group even if it has a lower plugin version than the group.

  • group_replication_allow_local_disjoint_gtids_join

    Introduced5.7.17
    Command-Line Format--group-replication-allow-local-disjoint-gtids-join=value
    System VariableNamegroup_replication_allow_local_disjoint_gtids_join
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeboolean
    DefaultOFF

    Allow the current server to join the group even if it has transactions not present in the group.

    Warning

    Use caution when enabling this option as incorrect usage could lead to inconsistencies in the group.

  • group_replication_auto_increment_increment

    Introduced5.7.17
    Command-Line Format--group-replication-auto-increment-increment=value
    System VariableNamegroup_replication_auto_increment_increment
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeinteger
    Default7
    Min Value1
    Max Value65535

    Determines the interval between successive column values for transactions that execute on this server instance.

  • group_replication_compression_threshold

    Introduced5.7.17
    Command-Line Format--group-replication-compression-threshold=value
    System VariableNamegroup_replication_compression_threshold
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeinteger
    Default1000000
    Min Value0
    Max Value4294967296

    The value in bytes above which (LZ4) compression is enforced. When set to zero, deactivates compression.

  • group_replication_gtid_assignment_block_size

    Introduced5.7.17
    Command-Line Format--group-replication-gtid-assignment-block-size=value
    System VariableNamegroup_replication_gtid_assignment_block_size
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted Values (32-bit platforms)Typeinteger
    Default1000000
    Min Value1
    Max Value4294967295
    Permitted Values (64-bit platforms)Typeinteger
    Default1000000
    Min Value1
    Max Value18446744073709547520

    The number of consecutive GTIDs that are reserved for each member. Each member consumes its blocks and reserves more when needed.

  • group_replication_ssl_mode

    Introduced5.7.17
    Command-Line Format--group-replication-ssl-mode=value
    System VariableNamegroup_replication_ssl_mode
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeenumeration
    DefaultDISABLED
    Valid ValuesDISABLED
    REQUIRED
    VERIFY_CA
    VERIFY_IDENTITY

    Specifies the security state of the connection between Group Replication members.

  • group_replication_single_primary_mode

    Introduced5.7.17
    Command-Line Format--group-replication-single-primary-mode=value
    System VariableNamegroup_replication_single_primary_mode
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeboolean
    DefaultON

    Instructs the group to automatically pick a single server to be the one that handles read/write workload. This server is the PRIMARY and all others are SECONDARIES.

  • group_replication_enforce_update_everywhere_checks

    Introduced5.7.17
    Command-Line Format--group-replication-enforce-update-everywhere-checks=value
    System VariableNamegroup_replication_enforce_update_everywhere_checks
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeboolean
    DefaultOFF

    Enable or disable strict consistency checks for multi-master update everywhere.

  • group_replication_flow_control_mode

    Introduced5.7.17
    Command-Line Format--group-replication-flow-control-mode=value
    System VariableNamegroup_replication_flow_control_mode
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeenumeration
    DefaultQUOTA
    Valid ValuesDISABLED
    QUOTA

    Specifies the mode used for flow control. This variable can be changed without resetting Group Replication.

  • group_replication_flow_control_certifier_threshold

    Introduced5.7.17
    Command-Line Format--group-replication-flow-control-certifier-threshold=value
    System VariableNamegroup_replication_flow_control_certifier_threshold
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeinteger
    Default25000
    Min Value0
    Max Value2147483648

    Specifies the number of waiting transactions in the certifier queue that trigger flow control. This variable can be changed without resetting Group Replication.

  • group_replication_flow_control_applier_threshold

    Introduced5.7.17
    Command-Line Format--group-replication-flow-control-applier-threshold=value
    System VariableNamegroup_replication_flow_control_applier_threshold
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypeinteger
    Default25000
    Min Value0
    Max Value2147483648

    Specifies the number of waiting transactions in the applier queue that trigger flow control. This variable can be changed without resetting Group Replication.

  • group_replication_ip_whitelist

    Introduced5.7.17
    Command-Line Format--group-replication-ip-whitelist=value
    System VariableNamegroup_replication_recovery_ip_whitelist
    Variable ScopeGlobal
    Dynamic VariableYes
    Permitted ValuesTypestring
    DefaultAUTOMATIC

    Specifies which hosts are permitted to connect to the group. By default set to AUTOMATIC, which permits connections from private subnetworks active on the host. Active interfaces on the host are scanned and those with addresses on private subnetworks are automatically added to the permitted list. Alternatively you can specify the permitted hosts using a comma separated list of IPv4 addresses or subnet CIDR notation. For example 192.168.1.0/24,10.0.0.1.

    Note

    Address 127.0.0.1 is always permitted to connect, even when not specified using group_replication_ip_whitelist.


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