Package com.stardog.stark.query

Class QueryResults

java.lang.Object

com.stardog.stark.query.QueryResults

public final class QueryResults
extends java.lang.Object

Utilities for working with QueryResults

Since:

1.0

Version:

1.0

Author:

Michael Grove, Jeen Broekstra

Method Summary

Modifier and Type	Method	Description
static void	closeQuietly(QueryResult<?> theResult)	"Quietly" close the QueryResult; any exception throw while closing will simply be logged.
static void	consume(QueryResult<?> theResult)	Iterate over all of the results and close the result set.
static boolean	equals(SelectQueryResult tqr1, SelectQueryResult tqr2)	Compares two tuple query results and returns true if they are equal.
static boolean	equalsWithOrder(SelectQueryResult tqr1, SelectQueryResult tqr2)	Similar to equals(SelectQueryResult, SelectQueryResult) but also checks the order of binding sets.
static boolean	isSubset(SelectQueryResult tqr1, SelectQueryResult tqr2)	Compares two tuple query results and returns true if the the first is a subset of the other.
static void	report(SelectQueryResult theResult, SelectQueryResultHandler theHandler)	Iterate over the query result and send the results to the given handler
static <T> java.util.Optional<T>	singleResult(QueryResult<T> theResult)	Return the next result from the results and close the results.
static long	size(QueryResult<?> theResult)	Return the number of results present in this result set
static <T> java.util.List<T>	toList(QueryResult<T> theResult)	Return the results as a List

Methods inherited from class java.lang.Object

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

Method Detail

toList

public static <T> java.util.List<T> toList(QueryResult<T> theResult)

Return the results as a List

Parameters:

theResult - the query result

Returns:

the results as a `List`

Implementation Notes:

* This pulls all of the results into memory so it is not appropriate for a large result set. * The side effect of this call is that `theResult` is closed.

report

public static void report(@Nonnull
                          SelectQueryResult theResult,
                          @Nonnull
                          SelectQueryResultHandler theHandler)

Iterate over the query result and send the results to the given handler

Parameters:

theResult - the result

theHandler - the result handler

Throws:

QueryExecutionFailure - if the next result could not be computed

Implementation Notes:

The side effect of this call is that `theResult` is closed.

singleResult

@Nonnull
public static <T> java.util.Optional<T> singleResult(@Nonnull
                                                     QueryResult<T> theResult)

Return the next result from the results and close the results.

Parameters:

theResult - the result

Returns:

the next result

Throws:

QueryExecutionFailure - if the next result could not be computed

Implementation Notes:

The side effect of this call is that `theResult` is closed.

size

public static long size(@Nonnull
                        QueryResult<?> theResult)

Return the number of results present in this result set

Parameters:

theResult - the results

Returns:

the number of results

Throws:

QueryExecutionFailure - if the results count not be computed

Implementation Notes:

The side effect of this call is that `theResult` is exhausted and closed.

consume

public static void consume(@Nonnull
                           QueryResult<?> theResult)

Iterate over all of the results and close the result set. The results of the query are simply thrown away.

Parameters:

theResult - the results

Throws:

QueryExecutionFailure - if the execution failed in any way

closeQuietly

public static void closeQuietly(@Nonnull
                                QueryResult<?> theResult)

"Quietly" close the QueryResult; any exception throw while closing will simply be logged.

Parameters:

theResult - the result to close

equals

public static boolean equals(@Nonnull
                             SelectQueryResult tqr1,
                             @Nonnull
                             SelectQueryResult tqr2)
                      throws QueryExecutionFailure

Compares two tuple query results and returns true if they are equal. Tuple query results are equal if they contain the same set of BindingSets and have the same headers. Blank nodes identifiers are not relevant for equality, they are matched by trying to find compatible mappings between BindingSets. Note that the method consumes both query results fully.

Parameters:

tqr1 - the first SelectQueryResult to compare.

tqr2 - the second SelectQueryResult to compare.

Throws:

QueryExecutionFailure

Implementation Notes:

This will consume both sets of results and they will both be closed as a side effect of calling this method. The results are also pulled into memory for the comparison, so this may not be suitable for use for large result sets.

equalsWithOrder

public static boolean equalsWithOrder(@Nonnull
                                      SelectQueryResult tqr1,
                                      @Nonnull
                                      SelectQueryResult tqr2)

Similar to equals(SelectQueryResult, SelectQueryResult) but also checks the order of binding sets.

isSubset

public static boolean isSubset(@Nonnull
                               SelectQueryResult tqr1,
                               @Nonnull
                               SelectQueryResult tqr2)
                        throws QueryExecutionFailure

Compares two tuple query results and returns true if the the first is a subset of the other. Uses the same notion of BindingSet equality as equals(SelectQueryResult, SelectQueryResult).

Parameters:

tqr1 - the first SelectQueryResult to compare.

tqr2 - the second SelectQueryResult to compare.

Throws:

QueryExecutionFailure

Implementation Notes:

This will consume both sets of results and they will both be closed as a side effect of calling this method. The results are also pulled into memory for the comparison, so this may not be suitable for use for large result sets.