The following performance issues are specific to or especially pronounced in MySQL Cluster:
Range scans. There are query performance issues due to sequential access to the
NDBstorage engine; it is also relatively more expensive to do many range scans than it is with either
Reliability of Records in range. The
Records in rangestatistic is available but is not completely tested or officially supported. This may result in nonoptimal query plans in some cases. If necessary, you can employ
FORCE INDEXto alter the execution plan. See Section 8.9.3, “Index Hints”, for more information on how to do this.
Unique hash indexes. Unique hash indexes created with
USING HASHcannot be used for accessing a table if
NULLis given as part of the key.