Cost cached plans with a dedicated cost model instead of their plan hash

fdb-record-layer-core/src/main/java/com/apple/foundationdb/record/query/plan/cascades/costing/PickRightTiebreaker.java

@@ -42,7 +42,7 @@
  * in plan changes. See: <a href="https://github.com/FoundationDB/fdb-record-layer/issues/3998">Issue #3998</a>.
  * </p>
  */
-final class PickRightTiebreaker implements Tiebreaker<RelationalExpression> {
+public final class PickRightTiebreaker implements Tiebreaker<RelationalExpression> {
     private static final PickRightTiebreaker INSTANCE = new PickRightTiebreaker();
 
     private PickRightTiebreaker() {
@@ -57,7 +57,7 @@ public int compare(@Nonnull final RecordQueryPlannerConfiguration configuration,
     }
 
     @Nonnull
-    static PickRightTiebreaker pickRightTiebreaker() {
+    public static PickRightTiebreaker pickRightTiebreaker() {
         return INSTANCE;
     }
 }

fdb-record-layer-core/src/main/java/com/apple/foundationdb/record/query/plan/cascades/costing/PlanningCostModel.java

@@ -336,27 +336,27 @@ static SmallestCardinalityOfDataAccessesTiebreaker smallestCardinalityOfDataAcce
     }
 
     @Nonnull
-    static LowestNumUnsatisfiedFiltersTiebreaker lowestNumUnsatisfiedFiltersTiebreaker() {
+    public static Tiebreaker<RecordQueryPlan> lowestNumUnsatisfiedFiltersTiebreaker() {
         return LowestNumUnsatisfiedFiltersTiebreaker.INSTANCE;
     }
 
     @Nonnull
-    static LowestNumDataAccessesTiebreaker lowestNumDataAccessesTiebreaker() {
+    public static Tiebreaker<RecordQueryPlan> lowestNumDataAccessesTiebreaker() {
         return LowestNumDataAccessesTiebreaker.INSTANCE;
     }
 
     @Nonnull
-    static RecursiveCteOperatorTiebreaker recursiveCteOperatorTiebreaker() {
+    public static Tiebreaker<RecordQueryPlan> recursiveCteOperatorTiebreaker() {
         return RecursiveCteOperatorTiebreaker.INSTANCE;
     }
 
     @Nonnull
-    static InOperatorTiebreaker inOperatorTiebreaker() {
+    public static Tiebreaker<RecordQueryPlan> inOperatorTiebreaker() {
         return InOperatorTiebreaker.INSTANCE;
     }
 
     @Nonnull
-    static PrimaryScanVsIndexScanTiebreaker primaryScanVsIndexScanTiebreaker() {
+    public static Tiebreaker<RecordQueryPlan> primaryScanVsIndexScanTiebreaker() {
         return PrimaryScanVsIndexScanTiebreaker.INSTANCE;
     }
 
@@ -366,22 +366,22 @@ static VectorIndexEnginePreferenceTiebreaker vectorIndexEnginePreferenceTiebreak
     }
 
     @Nonnull
-    static LowestTypeFilterCountTiebreaker lowestTypeFilterCountTiebreaker() {
+    public static Tiebreaker<RecordQueryPlan> lowestTypeFilterCountTiebreaker() {
         return LowestTypeFilterCountTiebreaker.INSTANCE;
     }
 
     @Nonnull
-    static DeepestTypeFilterPositionTiebreaker deepestTypeFilterPositionTiebreaker() {
+    public static Tiebreaker<RecordQueryPlan> deepestTypeFilterPositionTiebreaker() {
         return DeepestTypeFilterPositionTiebreaker.INSTANCE;
     }
 
     @Nonnull
-    static BetterIndexScanTiebreaker betterIndexScanTiebreaker() {
+    public static Tiebreaker<RecordQueryPlan> betterIndexScanTiebreaker() {
         return BetterIndexScanTiebreaker.INSTANCE;
     }
 
     @Nonnull
-    static DeepestDistinctTiebreaker deepestDistinctTiebreaker() {
+    public static Tiebreaker<RecordQueryPlan> deepestDistinctTiebreaker() {
         return DeepestDistinctTiebreaker.INSTANCE;
     }
 
@@ -391,12 +391,12 @@ static LowestNumUnmatchedFieldsTiebreaker lowestNumUnmatchedFieldsTiebreaker() {
     }
 
     @Nonnull
-    static HighestNumInJoinTiebreaker highestNumInJoinTiebreaker() {
+    public static Tiebreaker<RecordQueryPlan> highestNumInJoinTiebreaker() {
         return HighestNumInJoinTiebreaker.INSTANCE;
     }
 
     @Nonnull
-    static LowestNumSimpleOperationsTiebreaker lowestNumSimpleOperationsTiebreaker() {
+    public static Tiebreaker<RecordQueryPlan> lowestNumSimpleOperationsTiebreaker() {
         return LowestNumSimpleOperationsTiebreaker.INSTANCE;
     }
 
@@ -406,12 +406,12 @@ static LowestOuterCardinalityTiebreaker lowestOuterCardinalityTiebreaker() {
     }
 
     @Nonnull
-    static LowestNumDefaultOnEmptyTiebreaker lowestNumDefaultOnEmptyTiebreaker() {
+    public static Tiebreaker<RecordQueryPlan> lowestNumDefaultOnEmptyTiebreaker() {
         return LowestNumDefaultOnEmptyTiebreaker.INSTANCE;
     }
 
     @Nonnull
-    static PlanHashTiebreaker planHashTiebreaker() {
+    public static Tiebreaker<RecordQueryPlan> planHashTiebreaker() {
         return PlanHashTiebreaker.INSTANCE;
     }
 

fdb-record-layer-core/src/main/java/com/apple/foundationdb/record/query/plan/cascades/costing/Tiebreaker.java

@@ -61,7 +61,7 @@
  *
  * @param <T> the type of expressions being compared
  */
-interface Tiebreaker<T extends RelationalExpression> {
+public interface Tiebreaker<T extends RelationalExpression> {
 
     /**
      * Compare two expressions. Like a {@link java.util.Comparator}, this should return a

fdb-record-layer-core/src/main/java/com/apple/foundationdb/record/query/plan/cascades/costing/TiebreakerResult.java

@@ -26,7 +26,7 @@
 import java.util.Optional;
 import java.util.Set;
 
-interface TiebreakerResult<T extends RelationalExpression> {
+public interface TiebreakerResult<T extends RelationalExpression> {
 
     @Nonnull
     TiebreakerResult<T> thenApply(@Nonnull Tiebreaker<? super T> nextTiebreaker);

fdb-record-layer-core/src/test/java/com/apple/foundationdb/record/query/plan/cascades/costing/TiebreakerImplementationTests.java

@@ -153,4 +153,17 @@ void inOperatorTest() {
         assertCompares(inOperatorTiebreaker, inJoinSargedComparisonPlan, filterScanWithInPlan, 0);
         assertCompares(inOperatorTiebreaker, inJoinSargedComparisonPlan, inJoinNonSargedPlan, 0); // anti-symmetry violation!
     }
+
+    @Test
+    void planHashTest() {
+        final Tiebreaker<RecordQueryPlan> planHashTiebreaker = PlanningCostModel.planHashTiebreaker();
+        final RecordQueryPlan low = new RecordQueryPlanWithFixedPlanHash("low", 14);
+        final RecordQueryPlan high = new RecordQueryPlanWithFixedPlanHash("high", 30);
+        final RecordQueryPlan alsoLow = new RecordQueryPlanWithFixedPlanHash("alsoLow", 14);
+
+        assertReflexive(planHashTiebreaker, low);
+        assertCompares(planHashTiebreaker, low, high, -1);
+        assertCompares(planHashTiebreaker, high, low, 1);
+        assertCompares(planHashTiebreaker, low, alsoLow, 0);
+    }
 }