com.bigdata.bop.engine

Class BOpStats

java.lang.Object

com.bigdata.bop.engine.BOpStats

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

BaseJoinStats, NamedSolutionSetStats, ParserStats, SliceOp.SliceStats

public class BOpStats
extends Object
implements Serializable

Statistics associated with the evaluation of a BOp. These statistics are per BOp. The top-level BOp will reflect the throughput for the entire pipeline.

Version:

$Id$

Author:

Bryan Thompson

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
CAT	chunksIn #of chunks in.
CAT	chunksOut #of chunks out.
CAT	elapsed The elapsed time (milliseconds) for the corresponding operation.
CAT	mutationCount The #of tuples written onto a relation (not an index).
CAT	opCount The #of instances of a given operator which have been started (and successully terminated) for a given query.
CAT	typeErrors The #of error which were masked by the semantics of the query.
CAT	unitsIn #of units sets in (tuples, elements, binding sets, etc).
CAT	unitsOut #of units sets in (tuples, elements, binding sets, etc).

Constructor Summary

Constructors

Constructor and Description
BOpStats() Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
void	add(BOpStats o) Combine the statistics (addition), but do NOT add to self.
String	toString()
protected void	toString(StringBuilder sb) Extension hook for toString().

Methods inherited from class java.lang.Object

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

Field Detail

elapsed

public final CAT elapsed

The elapsed time (milliseconds) for the corresponding operation. When aggregated, this will generally exceed the wall time since concurrent processes are nearly always used during query evaluation.

opCount

public final CAT opCount

The #of instances of a given operator which have been started (and successully terminated) for a given query. This provides interesting information about the #of task instances for each operator which were required to execute a query.

See Also:

Explain reports incorrect value for opCount

chunksIn

public final CAT chunksIn

#of chunks in.

unitsIn

public final CAT unitsIn

#of units sets in (tuples, elements, binding sets, etc).

chunksOut

public final CAT chunksOut

#of chunks out.

unitsOut

public final CAT unitsOut

#of units sets in (tuples, elements, binding sets, etc).

typeErrors

public final CAT typeErrors

The #of error which were masked by the semantics of the query.

Note: SPARQL type errors in aggregations often cause bindings or solutions to fail without causing any runtime exception which can be observed at the query level. This counter provides a means to observe those errors.

mutationCount

public final CAT mutationCount

The #of tuples written onto a relation (not an index).

Note: This mutation counts should reflect the #of tuples written on a relation rather than on an index. The per-index tuple mutation count MAY also be reported, but it should be reported by extending this class and declaring additional mutation counters.

Note: Operations which fix point some closure depend on the correctness of the mutationCount for their termination condition.

Note: Mutation operations MUST NOT overwrite existing tuples with identical state. This is important for two reasons. First, fix point operations depend on the mutationCount being ZERO (0) in a given round if nothing was changed in order to terminate the closure. Second, due to the general MVCC and copy-on-write architecture, index writes drive IO. If the tuple state would not be changed, then the index write SHOULD NOT be performed.

Constructor Detail

BOpStats

public BOpStats()

Constructor.

Note: Do not pre-increment opCount. See add(BOpStats) and AbstractRunningQuery.haltOp(IHaltOpMessage).

See Also:

Explain reports incorrect value for opCount

Method Detail

add

public void add(BOpStats o)

Combine the statistics (addition), but do NOT add to self.

Parameters:

o - Another statistics object.

toString

public String toString()

Overrides:

toString in class Object

toString

protected void toString(StringBuilder sb)

Extension hook for toString().

Parameters:

sb - Where to write the additional state.