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




  • 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 can be run on the master aggregator node, or a child aggregator node (see Node Requirements for SingleStore 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, but you can remove orphaned database partitions on the leaf by running the ATTACH LEAF FORCE command followed by the CLEAR ORPHAN DATABASES command.

  • 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 .

  • This command causes implicit commits. Refer to COMMIT for more information.

  • See the Permission Matrix for the required permission.


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

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Last modified: July 31, 2023

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