Package com.tangosol.util.aggregator

Class QueryRecorder<K,V>

java.lang.Object

com.tangosol.util.aggregator.QueryRecorder<K,V>

Type Parameters:

K - the type of the Map entry keys

V - the type of the Map entry values

All Implemented Interfaces:

ExternalizableLite, PortableObject, InvocableMap.EntryAggregator<K,V,QueryRecord>, InvocableMap.StreamingAggregator<K,V,QueryRecord.PartialResult,QueryRecord>, Serializable

public class QueryRecorder<K,V>
extends Object
implements InvocableMap.StreamingAggregator<K,V,QueryRecord.PartialResult,QueryRecord>, ExternalizableLite, PortableObject

This aggregator is used to produce a QueryRecord object that contains an estimated or actual cost of the query execution for a given filter.

For example, the following code will print a QueryRecord, containing the estimated query cost and corresponding execution steps.

   QueryRecorder agent  = new QueryRecorder(RecordType.EXPLAIN);
   QueryRecord   record = (QueryRecord) cache.aggregate(filter, agent);
   System.out.println(record);
 

Author:

tb 2011.05.26

See Also:

• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	QueryRecorder.RecordType	RecordType enum specifies whether the QueryRecorder should be used to produce a QueryRecord object that contains an estimated or an actual cost of the query execution.

Field Summary

Fields inherited from interface com.tangosol.util.InvocableMap.StreamingAggregator

ALLOW_INCONSISTENCIES, BY_MEMBER, BY_PARTITION, PARALLEL, PRESENT_ONLY, RETAINS_ENTRIES, SERIAL

Constructor Summary

Constructors

Constructor	Description
QueryRecorder()	Default constructor (necessary for the ExternalizableLite interface).
QueryRecorder(QueryRecorder.RecordType type)	Construct a QueryRecorder.

Method Summary

Modifier and Type	Method	Description
boolean	accumulate(InvocableMap.Entry<? extends K,? extends V> entry)	Accumulate one entry into the result.
boolean	accumulate(Streamer<? extends InvocableMap.Entry<? extends K,? extends V>> streamer)	Accumulate multiple entries into the result.
QueryRecord	aggregate(Set<? extends InvocableMap.Entry<? extends K,? extends V>> setEntries)	Process a set of InvocableMap.Entry objects in order to produce an aggregated result.
int	characteristics()	A bit mask representing the set of characteristics of this aggregator.
boolean	combine(QueryRecord.PartialResult partialResult)	Merge another partial result into the result.
QueryRecord	finalizeResult()	Return the final result of the aggregation.
QueryRecord.PartialResult	getPartialResult()	Return the partial result of the aggregation.
QueryRecorder.RecordType	getType()	Get the record type for this query recorder.
void	readExternal(PofReader in)	Restore the contents of a user type instance by reading its state using the specified PofReader object.
void	readExternal(DataInput in)	Restore the contents of this object by loading the object's state from the passed DataInput object.
InvocableMap.StreamingAggregator<K,V,QueryRecord.PartialResult,QueryRecord>	supply()	Create a new instance of this aggregator.
void	writeExternal(PofWriter out)	Save the contents of a POF user type instance by writing its state using the specified PofWriter object.
void	writeExternal(DataOutput out)	Save the contents of this object by storing the object's state into the passed DataOutput object.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.tangosol.util.InvocableMap.StreamingAggregator

isAllowInconsistencies, isByMember, isByPartition, isParallel, isPresentOnly, isRetainsEntries, isSerial

Constructor Details

QueryRecorder

public QueryRecorder()

Default constructor (necessary for the ExternalizableLite interface).

QueryRecorder

public QueryRecorder(QueryRecorder.RecordType type)

Construct a QueryRecorder.

Parameters:

type - the type for this aggregator

Method Details

getType

public QueryRecorder.RecordType getType()

Get the record type for this query recorder.

Returns:

the record type enum

aggregate

public QueryRecord aggregate(Set<? extends InvocableMap.Entry<? extends K,? extends V>> setEntries)

Process a set of InvocableMap.Entry objects in order to produce an aggregated result.

Specified by:

aggregate in interface InvocableMap.EntryAggregator<K,V,QueryRecord>

Specified by:

aggregate in interface InvocableMap.StreamingAggregator<K,V,QueryRecord.PartialResult,QueryRecord>

Parameters:

setEntries - a Set of read-only InvocableMap.Entry objects to aggregate

Returns:

the aggregated result from processing the entries

supply

public InvocableMap.StreamingAggregator<K,V,QueryRecord.PartialResult,QueryRecord> supply()

Description copied from interface: InvocableMap.StreamingAggregator

Create a new instance of this aggregator.

Specified by:

supply in interface InvocableMap.StreamingAggregator<K,V,QueryRecord.PartialResult,QueryRecord>

Returns:

a StreamAggregator

accumulate

public boolean accumulate(Streamer<? extends InvocableMap.Entry<? extends K,? extends V>> streamer)

Description copied from interface: InvocableMap.StreamingAggregator

Accumulate multiple entries into the result.

Important note: The default implementation of this method provides necessary logic for aggregation short-circuiting and should rarely (if ever) be overridden by the custom aggregator implementation.

Specified by:

accumulate in interface InvocableMap.StreamingAggregator<K,V,QueryRecord.PartialResult,QueryRecord>

Parameters:

streamer - a Streamer that can be used to iterate over entries to add

Returns:

true to continue the aggregation, and false to signal to the caller that the result is ready and the aggregation can be short-circuited

accumulate

public boolean accumulate(InvocableMap.Entry<? extends K,? extends V> entry)

Description copied from interface: InvocableMap.StreamingAggregator

Accumulate one entry into the result.

Specified by:

accumulate in interface InvocableMap.StreamingAggregator<K,V,QueryRecord.PartialResult,QueryRecord>

Parameters:

entry - the entry to accumulate into the aggregation result

Returns:

true to continue the aggregation, and false to signal to the caller that the result is ready and the aggregation can be short-circuited

combine

public boolean combine(QueryRecord.PartialResult partialResult)

Description copied from interface: InvocableMap.StreamingAggregator

Merge another partial result into the result.

Specified by:

combine in interface InvocableMap.StreamingAggregator<K,V,QueryRecord.PartialResult,QueryRecord>

Parameters:

partialResult - the partial result to merge

Returns:

true to continue the aggregation, and false to signal to the caller that the result is ready and the aggregation can be short-circuited

getPartialResult

public QueryRecord.PartialResult getPartialResult()

Description copied from interface: InvocableMap.StreamingAggregator

Return the partial result of the aggregation.

Specified by:

getPartialResult in interface InvocableMap.StreamingAggregator<K,V,QueryRecord.PartialResult,QueryRecord>

Returns:

the partial result of the aggregation

finalizeResult

public QueryRecord finalizeResult()

Description copied from interface: InvocableMap.StreamingAggregator

Return the final result of the aggregation.

Specified by:

finalizeResult in interface InvocableMap.StreamingAggregator<K,V,QueryRecord.PartialResult,QueryRecord>

Returns:

the final result of the aggregation

characteristics

public int characteristics()

Description copied from interface: InvocableMap.StreamingAggregator

A bit mask representing the set of characteristics of this aggregator.

By default, characteristics are a combination of InvocableMap.StreamingAggregator.PARALLEL and InvocableMap.StreamingAggregator.RETAINS_ENTRIES, which is sub-optimal and should be overridden by the aggregator implementation if the aggregator does not need to retain entries (which is often the case).

Specified by:

characteristics in interface InvocableMap.StreamingAggregator<K,V,QueryRecord.PartialResult,QueryRecord>

Returns:

a bit mask representing the set of characteristics of this aggregator

See Also:

• InvocableMap.StreamingAggregator.ALLOW_INCONSISTENCIES
• InvocableMap.StreamingAggregator.BY_MEMBER
• InvocableMap.StreamingAggregator.BY_PARTITION
• InvocableMap.StreamingAggregator.PARALLEL
• InvocableMap.StreamingAggregator.PRESENT_ONLY
• InvocableMap.StreamingAggregator.RETAINS_ENTRIES
• InvocableMap.StreamingAggregator.SERIAL

readExternal

public void readExternal(DataInput in)
                  throws IOException

Restore the contents of this object by loading the object's state from the passed DataInput object.

Specified by:

readExternal in interface ExternalizableLite

Parameters:

in - the DataInput stream to read data from in order to restore the state of this object

Throws:

IOException - if an I/O exception occurs

writeExternal

public void writeExternal(DataOutput out)
                   throws IOException

Save the contents of this object by storing the object's state into the passed DataOutput object.

Specified by:

writeExternal in interface ExternalizableLite

Parameters:

out - the DataOutput stream to write the state of this object to

Throws:

IOException - if an I/O exception occurs

readExternal

public void readExternal(PofReader in)
                  throws IOException

Restore the contents of a user type instance by reading its state using the specified PofReader object.

Specified by:

readExternal in interface PortableObject

Parameters:

in - the PofReader from which to read the object's state

Throws:

IOException - if an I/O error occurs

writeExternal

public void writeExternal(PofWriter out)
                   throws IOException

Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Specified by:

writeExternal in interface PortableObject

Parameters:

out - the PofWriter to which to write the object's state

Throws:

IOException - if an I/O error occurs