com.bigdata.relation.rule

Class QueryOptions

java.lang.Object

com.bigdata.relation.rule.QueryOptions

All Implemented Interfaces:

IQueryOptions, Serializable

public class QueryOptions
extends Object
implements IQueryOptions

Version:

$Id$

Author:

Bryan Thompson

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static IQueryOptions	DISTINCT An instance specifying distinct := true but none of the other IQueryOptions.
static IQueryOptions	NONE An instance specifying NONE of the constraints declared by IQueryOptions.

Constructor Summary

Constructors

Constructor and Description
QueryOptions(boolean distinct, boolean stable, ISortOrder[] orderBy, ISlice slice)

Method Summary

Methods

Modifier and Type	Method and Description
ISortOrder[]	getOrderBy() An optional array of ISortOrders describing the sort order that will be imposed on the generated solutions when the rule is evaluated as a query.
ISlice	getSlice() An optional ISlice describing a constraint on the first solution and the maximum #of solutions to be materialized by a query.
boolean	isDistinct() true if a DistinctFilter should be applied when the query is evaluated.
boolean	isStable() Return true iff query evaluation must be stable.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

NONE

public static final transient IQueryOptions NONE

An instance specifying NONE of the constraints declared by IQueryOptions.

DISTINCT

public static final transient IQueryOptions DISTINCT

An instance specifying distinct := true but none of the other IQueryOptions.

Constructor Detail

QueryOptions

public QueryOptions(boolean distinct,
            boolean stable,
            ISortOrder[] orderBy,
            ISlice slice)

Parameters:

distinct -

stable -

orderBy -

slice -

Throws:

IllegalArgumentException - if a stable is false and a slice is specified with a non-zero offset and/or a non-Long.MAX_VALUE limit

Method Detail

isDistinct

public final boolean isDistinct()

Description copied from interface: IQueryOptions

true if a DistinctFilter should be applied when the query is evaluated.

Specified by:

isDistinct in interface IQueryOptions

isStable

public final boolean isStable()

Description copied from interface: IQueryOptions

Return true iff query evaluation must be stable. Stable query evaluation requires that the same query executed against the same commit point will produce the same solutions in the same order. This constraint requires that (a) query execution does not use any parallelism; and (b) all IStepTask are determinate. Stable queries may be useful when using an ISlice to page through a solution set.

Specified by:

isStable in interface IQueryOptions

Returns:

true if query evaluation must be stable.

getOrderBy

public final ISortOrder[] getOrderBy()

Description copied from interface: IQueryOptions

An optional array of ISortOrders describing the sort order that will be imposed on the generated solutions when the rule is evaluated as a query.

Specified by:

getOrderBy in interface IQueryOptions

Returns:

An array of ISortOrders -or- null iff there is no "order by" constraint.

getSlice

public final ISlice getSlice()

Description copied from interface: IQueryOptions

An optional ISlice describing a constraint on the first solution and the maximum #of solutions to be materialized by a query.

Note: Using an ISlice requires that the solutions are stable for queries against the same commit point of the database.

Specified by:

getSlice in interface IQueryOptions

Returns:

The ISlice -or- null if there is no constraint on the solutions that will be visited.

toString

public String toString()

Overrides:

toString in class Object