Comunica
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    Class ActorRdfJoinOptionalOptPlus

    A comunica Optional Opt+ RDF Join Actor.

    Hierarchy (View Summary)

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    Constructors

    constructor

    Properties

    beforeActors bus canHandleOperationRequired? canHandleUndefs includeInLogs isLeaf limitEntries limitEntriesMin logicalType mediatorJoin mediatorJoinSelectivity name physicalName pushesBindingsToSource? requiresVariableOverlap?

    Methods

    constructResultMetadata constructState getDefaultLogData getJoinCoefficients getOutput logDebug logError logFatal logInfo logTrace logWarn run runObservable test getCardinality getContextLogger getEntriesWithMetadatas getMetadatas getRequestInitialTimes getRequestItemTimes getSharedVariableJoinCardinality joinBindings joinVariables overlappingVariables sortJoinEntries

    Constructors

    Properties

    beforeActors: Actor<
        IActionRdfJoin,
        IMediatorTypeJoinCoefficients,
        IQueryOperationResultBindings,
        IActorRdfJoinTestSideData,
    >[] = []

    Actor that must be registered in the bus before this actor.

    bus: Bus<
        Actor<
            IActionRdfJoin,
            IMediatorTypeJoinCoefficients,
            IQueryOperationResultBindings,
            IActorRdfJoinTestSideData,
        >,
        IActionRdfJoin,
        IMediatorTypeJoinCoefficients,
        IQueryOperationResultBindings,
        IActorRdfJoinTestSideData,
    >

    The bus this actor subscribes to.

    canHandleOperationRequired?: boolean

    If this join operator can handle join entries with operationModified set to true. This will typically only be true for bind-join-like operators.

    canHandleUndefs: boolean

    If this actor can handle undefs overlapping variable bindings.

    includeInLogs: boolean = true

    If this actor will be logged in the debugger and physical query plan logger

    isLeaf: boolean

    If this join operator will not invoke any other join or query operations below, and can therefore be considered a leaf of the join plan.

    limitEntries: number

    Can be used by subclasses to indicate the max or min number of streams that can be joined. 0 for infinity. By default, this indicates the max number, but can be inverted by setting limitEntriesMin to true.

    limitEntriesMin: boolean

    If true, the limitEntries field is a lower limit, otherwise, it is an upper limit.

    logicalType: LogicalJoinType
    mediatorJoin: MediatorRdfJoin
    mediatorJoinSelectivity: MediatorRdfJoinSelectivity
    name: string

    The name for this actor.

    {<rdf:subject>}
    physicalName: string
    pushesBindingsToSource?: boolean

    If this actor pushes bindings of one entry into the source of another entry.

    requiresVariableOverlap?: boolean

    If this join operator must only be used for join entries with (at least partially) common variables.

    Methods

    • Estimate the cardinality of an equi-join from the cardinalities of its entries.

      Under the usual uniformity assumption, joining two entries on a shared variable divides their cross product by the number of distinct values that variable takes. That number is unknown here, so it is approximated by the cardinality of the largest entry binding the variable, which is its upper bound. For two entries sharing a variable this yields the cardinality of the smaller entry.

      Only the most selective shared variable is taken into account. Entries sharing several variables are more selective still, but applying the approximation once per variable compounds its error, which would collapse the estimate far below the smallest entry.

      Parameters

      Returns number | undefined

      The estimated cardinality, or undefined if the entries share no variables.

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