NDB Cluster Configuration Files ndb_metadata_sync  is then set to  false , and the change monitor thread reverts to the behavior determined by the settings for  ndb_metadata_check  and  ndb_metadata_check_interval . In NDB 8.0.22 and later, setting this variable to  true  causes the list of excluded objects to be cleared, and setting it to  false  clears the list of objects to be retried. • ndb_optimized_node_selection Command-Line Format --ndb-optimized-node-selection=# System Variable ndb_optimized_node_selection Scope Global Dynamic No SET_VAR  Hint Applies No Type Integer Default Value 3 Minimum Value 0 Maximum Value 3 There are two forms of optimized node selection, described here: 1. The SQL node uses  promixity  to determine the transaction coordinator; that is, the “closest”  data node to the SQL node is chosen as the transaction coordinator. For this purpose, a data node having a shared memory connection with the SQL node is considered to be “closest”  to the SQL node; the next closest (in order of decreasing proximity) are: TCP connection to  localhost , followed by TCP connection from a host other than  localhost . 2. The SQL thread uses  distribution awareness  to select the data node. That is, the data node housing the cluster partition accessed by the first statement of a given transaction is used as the transaction coordinator for the entire transaction. (This is effective only if the first statement of the transaction accesses no more than one cluster partition.) • 0 : Node selection is not optimized. Each data node is employed as the transaction coordinator 8 times before the SQL thread proceeds to the next data node. • 1 : Proximity to the SQL node is used to determine the transaction coordinator. • 2 : Distribution awareness is used to select the transaction coordinator. However, if the first statement of the transaction accesses more than one cluster partition, the SQL node reverts to the round-robin behavior seen when this option is set to  0 . • 3 : If distribution awareness can be employed to determine the transaction coordinator, then it is used; otherwise proximity is used to select the transaction coordinator. (This is the default behavior.) 1. Start with the value set for the  Group  parameter (default 55). 2. For an API node sharing the same host with other API nodes, decrement the value by 1. Assuming the default value for  Group , the effective value for data nodes on same host as the API node is 54, and for remote data nodes 55. This option takes one of the integer values  0 ,  1 ,  2 , or  3 .  3  is the default. These values affect node selection as follows: Proximity is determined as follows: 4186