The following performance issues are specific to or especially pronounced in NDB Cluster:
Range scans. There are query performance issues due to sequential access to the
NDB
storage engine; it is also relatively more expensive to do many range scans than it is with eitherMyISAM
orInnoDB
.Reliability of Records in range. The
Records in range
statistic is available but is not completely tested or officially supported. This may result in nonoptimal query plans in some cases. If necessary, you can employUSE INDEX
orFORCE INDEX
to alter the execution plan. See Section 10.9.4, “Index Hints”, for more information on how to do this.Unique hash indexes. Unique hash indexes created with
USING HASH
cannot be used for accessing a table ifNULL
is given as part of the key.