Package org.apache.jena.sparql.engine.join

Class Join

java.lang.Object

org.apache.jena.sparql.engine.join.Join

public class Join
extends java.lang.Object

API to various join algorithms

Constructor Summary

Constructors

Constructor	Description
Join()

Method Summary

Modifier and Type	Method	Description
static QueryIterator	hashJoin(JoinKey joinKey, QueryIterator left, QueryIterator right, ExecutionContext execCxt)	Evaluate using a hash join.
static QueryIterator	hashJoin(QueryIterator left, QueryIterator right, ExecutionContext execCxt)	Evaluate using a hash join.
static QueryIterator	hashLeftJoin(JoinKey joinKey, QueryIterator left, QueryIterator right, ExprList conditions, ExecutionContext execCxt)	Left outer join by using hash join.
static QueryIterator	hashLeftJoin(QueryIterator left, QueryIterator right, ExprList conditions, ExecutionContext execCxt)	Left outer join by using hash join.
static QueryIterator	join(QueryIterator left, QueryIterator right, ExecutionContext execCxt)	Standard entry point to a join of two streams.
static QueryIterator	leftJoin(QueryIterator left, QueryIterator right, ExprList conditions, ExecutionContext execCxt)	Standard entry point to a left join of two streams.
static QueryIterator	nestedLoopJoin(QueryIterator left, QueryIterator right, ExecutionContext execCxt)	Inner loop join.
static QueryIterator	nestedLoopJoinBasic(QueryIterator left, QueryIterator right, ExecutionContext execCxt)	Very simple, materializing version - useful for debugging.
static QueryIterator	nestedLoopLeftJoin(QueryIterator left, QueryIterator right, ExprList conditions, ExecutionContext execCxt)	Left loop join.
static QueryIterator	nestedLoopLeftJoinBasic(QueryIterator left, QueryIterator right, ExprList conditions, ExecutionContext execCxt)	Very simple, materializing version for leftjoin - useful for debugging.

Methods inherited from class java.lang.Object

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

Constructor Detail

Join

public Join()

Method Detail

join

public static QueryIterator join(QueryIterator left,
                                 QueryIterator right,
                                 ExecutionContext execCxt)

Standard entry point to a join of two streams. This is not a substitution/index join. (See OpExecutor for streamed execution using substitution).

Parameters:

left -

right -

execCxt -

Returns:

QueryIterator

leftJoin

public static QueryIterator leftJoin(QueryIterator left,
                                     QueryIterator right,
                                     ExprList conditions,
                                     ExecutionContext execCxt)

Standard entry point to a left join of two streams. This is not a substitution/index join. (See OpExecutor for streamed execution using substitution).

Parameters:

left -

right -

conditions -

execCxt -

Returns:

QueryIterator

nestedLoopJoin

public static QueryIterator nestedLoopJoin(QueryIterator left,
                                           QueryIterator right,
                                           ExecutionContext execCxt)

Inner loop join. Cancellable.

Parameters:

left - Left hand side

right - Right hand side

execCxt - ExecutionContext

Returns:

QueryIterator

nestedLoopLeftJoin

public static QueryIterator nestedLoopLeftJoin(QueryIterator left,
                                               QueryIterator right,
                                               ExprList conditions,
                                               ExecutionContext execCxt)

Left loop join. Cancellable.

Parameters:

left - Left hand side

right - Right hand side

execCxt - ExecutionContext

Returns:

QueryIterator

hashJoin

public static QueryIterator hashJoin(QueryIterator left,
                                     QueryIterator right,
                                     ExecutionContext execCxt)

Evaluate using a hash join.

Parameters:

left - Left hand side

right - Right hand side

execCxt - ExecutionContext

Returns:

QueryIterator

hashJoin

public static QueryIterator hashJoin(JoinKey joinKey,
                                     QueryIterator left,
                                     QueryIterator right,
                                     ExecutionContext execCxt)

Evaluate using a hash join.

Parameters:

joinKey - The key for the probe table.

left - Left hand side

right - Right hand side

execCxt - ExecutionContext

Returns:

QueryIterator

hashLeftJoin

public static QueryIterator hashLeftJoin(QueryIterator left,
                                         QueryIterator right,
                                         ExprList conditions,
                                         ExecutionContext execCxt)

Left outer join by using hash join. Normally, this is hashing the right hand side and streaming the left. The reverse implementation (hash left, stream right) is also available.

Parameters:

left -

right -

conditions -

execCxt -

Returns:

QueryIterator

hashLeftJoin

public static QueryIterator hashLeftJoin(JoinKey joinKey,
                                         QueryIterator left,
                                         QueryIterator right,
                                         ExprList conditions,
                                         ExecutionContext execCxt)

Left outer join by using hash join. Normally, this is hashing the right hand side and streaming the left. The reverse implementation (hash left, stream right) is also available.

Parameters:

joinKey -

left -

right -

conditions -

execCxt -

Returns:

QueryIterator

nestedLoopJoinBasic

public static QueryIterator nestedLoopJoinBasic(QueryIterator left,
                                                QueryIterator right,
                                                ExecutionContext execCxt)

Very simple, materializing version - useful for debugging. Builds output early. Materializes left, streams right. Does not scale. No cancellation, no stats.

See Also:

nestedLoopJoin(org.apache.jena.sparql.engine.QueryIterator, org.apache.jena.sparql.engine.QueryIterator, org.apache.jena.sparql.engine.ExecutionContext)

nestedLoopLeftJoinBasic

public static QueryIterator nestedLoopLeftJoinBasic(QueryIterator left,
                                                    QueryIterator right,
                                                    ExprList conditions,
                                                    ExecutionContext execCxt)

Very simple, materializing version for leftjoin - useful for debugging. Builds output early. Materializes right, streams left. Does not scale.