public class COUNT extends AggregateBase<IV>
Note: COUNT(*) is the cardinality of the solution multiset. COUNT(DISTINCT *) is the cardinality of the distinct solutions in the solution multiset. These semantics are not directly handled by this class. It relies on the aggregation operator to compute those values.
|Constructor and Description|
|Modifier and Type||Method and Description|
Return the final value.
Return the current value of the aggregate (this has a side-effect on the internal state of the
COUNT does not need to actually see the materialized values, or even the IVs.
Reset the aggregate's internal state.
_set, annotations, annotationsCopy, annotationsEqual, annotationsRef, argIterator, args, argsCopy, arity, clearAnnotations, clearProperty, deepCopy, deepCopy, get, getProperty, setArg, setProperty, setUnboundProperty, toArray, toArray
annotationsEqual, annotationsToString, annotationsToString, annotationValueToString, checkArgs, clone, equals, getEvaluationContext, getId, getProperty, getRequiredProperty, hashCode, indent, isController, shortenName, toShortString, toString, toString
finalize, getClass, notify, notifyAll, wait, wait, wait
annotations, argIterator, args, arity, clone, get, getEvaluationContext, getId, getProperty, getRequiredProperty, isController, setProperty, toArray, toArray, toShortString, toString
public COUNT(COUNT op)
public COUNT(BOp args, java.util.Map<java.lang.String,java.lang.Object> annotations)
public IV get(IBindingSet bindingSet)
IAggregateoperator). Functions which can not produce an intermediate result, such as AVERAGE, MAY return
Note: If evaluation of the
IAggregate throws an error, then that
error must be "sticky" and reported out by
IAggregate.done() as well. This
contract is relied on to correctly propagate errors within a group when
using incremental (pipelined) evaluation of
error state is cleared by
Operation is not implemented by this class and must be overridden if the
AggregateBase is to be directly evaluated. However, note that the
computation of aggregate functions is often based on hard coded
recognition of the appropriate function code.
Note: DISTINCT is merely carried as a marker on COUNT (and the other
aggregate functions). The application of DISTINCT to the inner expression
to form a column projection is handled by the driving evaluation logic
rather than by
Note: COUNT() returns ZERO if there are no non-error solutions presented. This assumes that the ZERO will be an xsd:long.
public void reset()
public INeedsMaterialization.Requirement getRequirement()
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