com.bigdata.btree.proc
Class RangeCountProcedure

java.lang.Object
  com.bigdata.btree.proc.AbstractIndexProcedure
      com.bigdata.btree.proc.AbstractKeyRangeIndexProcedure
          com.bigdata.btree.proc.RangeCountProcedure

All Implemented Interfaces:

IIndexProcedure, IKeyRangeIndexProcedure, IParallelizableIndexProcedure, Externalizable, Serializable

public class RangeCountProcedure
extends AbstractKeyRangeIndexProcedure
implements IParallelizableIndexProcedure

This procedure computes a range count on an index.

See Also:

Serialized Form

Field Summary

Fields inherited from class com.bigdata.btree.proc.AbstractKeyRangeIndexProcedure

fromKey, toKey

Constructor Summary

RangeCountProcedure()
De-serialization ctor.

RangeCountProcedure(boolean exact, boolean deleted, byte[] fromKey, byte[] toKey)
Range count using the specified bounds.

Method Summary

Object	apply(IIndex ndx) Range count of entries in a key range for the index.
boolean	isReadOnly() Return true iff the procedure asserts that it will not write on the index.
void	readExternal(ObjectInput in)
void	writeExternal(ObjectOutput out)

Methods inherited from class com.bigdata.btree.proc.AbstractKeyRangeIndexProcedure

constrainFromKey, constrainToKey, getFromKey, getToKey, readKeys, writeKeys

Methods inherited from class com.bigdata.btree.proc.AbstractIndexProcedure

getKeyBuilder

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RangeCountProcedure

public RangeCountProcedure()

De-serialization ctor.

RangeCountProcedure

public RangeCountProcedure(boolean exact,
                           boolean deleted,
                           byte[] fromKey,
                           byte[] toKey)

Range count using the specified bounds.

Parameters:

exact - iff an exact range count is required.

deleted - iff deleted tuples must be included in the count.

fromKey - The lower bound (inclusive) -or- null if there is no lower bound.

toKey - The upper bound (exclusive) -or- null if there is no upper bound.

Throws:

IllegalArgumentException - if exact is false and deleted is true (there is no approximate reporting for range counts of deleted and undeleted tuples).

Method Detail

isReadOnly

public final boolean isReadOnly()

Description copied from interface: IIndexProcedure

Return true iff the procedure asserts that it will not write on the index. When true, the procedure may be run against a view of the index that is read-only or which allows concurrent processes to read on the same index object. When false the procedure will be run against a mutable view of the index (assuming that the procedure is executed in a context that has access to a mutable index view).

Specified by:

isReadOnly in interface IIndexProcedure

apply

public Object apply(IIndex ndx)

Range count of entries in a key range for the index.

Note: When the index IndexMetadata.getDeleteMarkers() this method reports the upper bound estimate of the #of key-value pairs in the key range of the index. The estimate is an upper bound because duplicate or deleted entries in that have not been eradicated through a suitable compacting merge will be reported. An exact count may be obtained using a range iterator by NOT requesting either the keys or the values.

Specified by:

apply in interface IIndexProcedure

Parameters:

ndx - The index.

Returns:

The upper bound estimate of the #of key-value pairs in the key range of the named index.

readExternal

public void readExternal(ObjectInput in)
                  throws IOException,
                         ClassNotFoundException

Specified by:

readExternal in interface Externalizable

Overrides:

readExternal in class AbstractKeyRangeIndexProcedure

Throws:

IOException

ClassNotFoundException

writeExternal

public void writeExternal(ObjectOutput out)
                   throws IOException

Specified by:

writeExternal in interface Externalizable

Overrides:

writeExternal in class AbstractKeyRangeIndexProcedure

Throws:

IOException