Using pushdown predicates
To minimize the amount of data to be processed, enable pushdown predicates by using cql3.pushdown.enable in the TBLPROPERTIES clause of a Hive query.
Pushdown predicates resolve expressions as early as possible in the processing pipeline to minimize the amount of data to be processed. You enable pushdown predicates using a new property cql3.pushdown.enable in the TBLPROPERTIES clause of a Hive query. True enables the feature and false (the default) disables it. Processing of operations on columns of the following types are affected by the setting:
Cassandra type | Hive type |
---|---|
UTF8Type | string |
AsciiType | string |
CounterColumnType | long |
DateType | timestamp |
LongType | long |
DoubleType | double |
FloatType | float |
BooleanType | boolean |
Int32Type | int |
Recommended usage
When the indexed row is small, enable pushdown predicates; otherwise, disable the feature to avoid a timeout exception or Out-Of-Memory (OOM) condition.
Limitations
DataStax Enterprise supports pushdown predicates for indexes only. Primary keys are not supported.