ATTACH LEAF

Attaches a detached leaf into the cluster, re-introducing its data (if possible).

Syntax

ATTACH LEAF 'host':port [FORCE] [NO REBALANCE]

Remarks

  • ATTACH LEAF will transition the leaf from the detached state to the online state. ATTACH is used to reintroduce a leaf back into the system. By default, ATTACH LEAF also performs any rebalance and resyncing actions needed to bring the leaf up to date with the rest of the cluster. To attach a leaf without rebalancing partitions, use the NO REBALANCE option. For more information see REBALANCE PARTITIONS .
  • ATTACH LEAF can only be run on leaf nodes that are present in SHOW_LEAVES.
  • This command must be run on the master aggregator node (see Node Requirements for MemSQL Commands ).
  • The FORCE flag overrides any conflicts that would prevent ATTACH LEAF from running. In practice, this happens when the data on the leaf has diverged away from the current state of the cluster (for example, a database was recreated while the leaf was down). You do not need to ATTACH LEAF ... FORCE by default. ATTACH LEAF without the FORCE flag collects information about which databases on the leaf are conflicting and the error message indicates directly that you should add the FORCE flag. By specifying the FORCE flag, you enable ATTACH LEAF to ignore the conflicting data on the node you are attaching. The FORCE flag does not drop the conflicting databases on the node. You can also manually resolve these conflicts by connecting to the leaf directly, examining the conflicting databases, and dropping them if they are no longer relevant.
  • If you want to reattach many leaves at one time, after restarting a cluster, for example, you can use ATTACH LEAF ALL.
  • Detached leaves automatically reattach. To disable this feature, set the global variable auto_attach to false. For more information see SET GLOBAL .

Example

memsql> ATTACH LEAF '192.168.1.110':3306;
Query OK, 1 row affected (1.11 sec)

Related Topics

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