Package com.apple.foundationdb.record.query.plan.temp.view

Interface Element

  • All Superinterfaces:
    Correlated<Element>, PlanHashable
    All Known Implementing Classes:
    FieldElement, LiteralElement, RecordTypeElement, ValueElement, VersionElement
    @API(EXPERIMENTAL)
public interface Element
extends PlanHashable, Correlated<Element>
    A value in the ViewExpression language that can be represented as an element of FoundationDB tuple.

    An element is the atom of a FoundationDB tuple, and therefore has a representation as a byte string with a defined total order (i.e., an order where a <= b and b <= a implies that a == b, and where either a <= b or b <= a). Elements generate the values that can be used to define the projection, predicate, sort order, or grouping of a view expression. Since elements must be usable in FoundationDB tuples, they are also the fundamental unit of key planning operations such as incremental index selection. Many, but not all, elements reference a Source which identifies what streams of data will generate them.

    • Method Detail

      • matchWith

        @Nonnull
Optional<ComparisonRange> matchWith​(@Nonnull
                                    ComparisonRange existingComparisons,
                                    @Nonnull
                                    ElementPredicate predicate)
        Determine whether this element can be used to satisfy the given ElementPredicate, under the assumption that this element is already being used to satisfy the given ComparisonRange. Note that this method relies on strict comparisons between elements, i.e., the sources must be reference-equal to each other.
        Parameters:
        existingComparisons - a range of existing comparisons that the planner is using this element to support
        predicate - an element predicate to match with this element and the given comparison range
        Returns:
        a new comparison range incorporating the predicate's comparison if the match was successful, Optional.empty() otherwise

      • matchSourcesWith

        @Nonnull
Optional<ViewExpressionComparisons> matchSourcesWith​(@Nonnull
                                                     ViewExpressionComparisons viewExpressionComparisons,
                                                     @Nonnull
                                                     Element element)
        Determine whether this element is the same as the given Element when unused sources are combined with each other. Sources are determined to be used or unused based on their usage in the given ViewExpressionComparisons. A source is used if any element using that source has a comparison already matched to it; otherwise, it is unused. If an available match is found, produce a version of the given ViewExpressionComparisons with all instances of this element's source replaced with the given element's source.

        This method makes it possible to match ElementPredicates generated by normalizing a QueryComponent with those generated by normalizing a KeyExpression. These normalization processes are decoupled so the sources for each will not match in general; therefore, matchWith(ComparisonRange, ElementPredicate) will fail to notice when an index defined by a KeyExpression can support a predicate.

        Parameters:
        viewExpressionComparisons - view expression comparisons that determine which sources are used and unused
        element - an element to compare with this one and look for matches made through combining sources
        Returns:
        a new view expression comparisons with instances of this element's source replaced with the given element's if a match is found, Optional.empty() otherwise

      • getAncestralSources

        @Nonnull
Set<Source> getAncestralSources()
        Get the set of all sources for this element, including all ancestors of this element's sources.
        Returns:
        a set of the sources of all (inclusive) ancestors of this element's sources

      • withSourceMappedInto

        @Nonnull
Element withSourceMappedInto​(@Nonnull
                             Source originalSource,
                             @Nonnull
                             Source duplicateSource)
        Replace the given duplicate source with the given original source everywhere that it occurs in this element, including in ancestor sources of this element's source.
        Parameters:
        originalSource - a source to replace all occurrences of the duplicate source with
        duplicateSource - a source to replace with the original source
        Returns:
        a copy of this element with all occurrences of the duplicate source replaced with the original source

      • eval

        @Nullable
Object eval​(@Nonnull
            SourceEntry sourceEntry)
        Evaluate this element with respect to the given source entry, producing an object that can be interpreted by a Comparisons.Comparison.
        Parameters:
        sourceEntry - a source entry to use when evaluating this element
        Returns:
        the value of this element on the given source entry