Package com.apple.foundationdb.record.query.predicates

Class ValueComparisonRangePredicate

    • Constructor Detail

      • ValueComparisonRangePredicate

        public ValueComparisonRangePredicate​(@Nonnull
                                     Value value)

    • Method Detail

      • semanticEquals

        public boolean semanticEquals​(@Nullable
                              Object other,
                              @Nonnull
                              AliasMap aliasMap)
        Description copied from interface: Correlated
        Determine equality with respect to an equivalence map between CorrelationIdentifiers based on semantic equality: equality of the plan fragments implementing under the given correlation bindings. The contract of this variant of equals() differs from its regular Java counterpart. A correlation is mostly just one part inside of composition of objects that expresses a more complicated (correlated) structure such as a filter. For instance q1.x = 5 uses a correlation to q1. That entity representing the filter is said to be correlated to q1. Similarly, q1.x = 6 is a different filter and is not equal under any correlation mapping. In contrast, consider a predicate where everything except the correlation is the same, such as q2.x = 5. Without a binding, these two filters are not the same. However, the filters may be a part of some other entity that can express correlations: SELECT * FROM T as q1 WHERE q1.x = 5 is equal to SELECT * FROM T as q2 WHERE q2.x = 5. It does not matter that q1 and q2 are named differently. It is important, however, that their semantic meaning is the same. In the example both q1 and q2 refer to a record type T which presumably is the same record type. Therefore, these two query blocks are the same, even though they are labelled differently. In the context of this method, we can establish equality between q1.x = 5 and q2.x = 5 if we know that q1 and q2 refer to the same underlying entity. The equivalence map passed in encodes that equality between CorrelationIdentifiers. Note: This method has the same interaction with Object.hashCode() as the regular equals() method. As we can only ever establish true equality using equivalence maps, hashCode() implementations in implementors of this interface must not be dependent on any correlation identifiers used in the structure of the entity. Doing so might violate the fundamental property of hash codes: e1.equals(e2, ...) => e1.hashCode() == e2.hashCode()
        Specified by:
        semanticEquals in interface Correlated<QueryPredicate>
        Parameters:
        other - the other object to establish equality with
        aliasMap - a map of CorrelationIdentifiers ids to ids'. A correlation identifier id used in this should be considered equal to another correlation identifier id' used in other if either they are the same by Object.equals(java.lang.Object) of if there is a mapping from id to id'.
        Returns:
        true if both entities are considered equal using the equivalences passed in, false otherwise

      • hashCode

        public int hashCode()
        Overrides:
        hashCode in class Object

      • semanticHashCode

        public int semanticHashCode()
        Description copied from interface: Correlated
        Return a semantic hash code for this object. The hash code must obey the convention that for any two objects o1 and o2 and for every AliasMap aliasMap: 
         o1.semanticEquals(o1, aliasMap) follows o1.semanticHash() == o2.semanticHash()
        If the semantic hash code of two implementing objects is equal and Correlated.semanticEquals(java.lang.Object, com.apple.foundationdb.record.query.plan.temp.AliasMap) returns true for these two objects the plan fragments are considered to produce the same result under the given correlations bindings. The left side o1.semanticEquals(o1, aliasMap) depends on an AliasMap while o1.semanticHash() == o2.semanticHash() does not. Hence, the hash that is computed is identical regardless of possible bindings.
        Specified by:
        semanticHashCode in interface Correlated<QueryPredicate>
        Returns:
        the semantic hash code

      • planHash

        public int planHash​(@Nonnull
                    PlanHashable.PlanHashKind hashKind)
        Description copied from interface: PlanHashable
        Return a hash similar to hashCode, but with the additional guarantee that is is stable across JVMs.
        Specified by:
        planHash in interface PlanHashable
        Parameters:
        hashKind - the "kind" of hash to calculate. Each kind of hash has a particular logic with regards to included and excluded items.
        Returns:
        a stable hash code