Fixes list/bag ExprValue creation in plan evaluator

lang/src/main/kotlin/org/partiql/lang/ast/IsOrderedMeta.kt

@@ -0,0 +1,9 @@
+package org.partiql.lang.ast
+
+/**
+ * To reduce any extraneous passes over data, this [Meta] indicates whether the associated BindingsToValues Physical
+ * expression should be an ordered list or a bag.
+ */
+object IsOrderedMeta : Meta {
+    override val tag = "\$is_ordered"
+}

lang/src/main/kotlin/org/partiql/lang/eval/physical/PhysicalPlanCompilerImpl.kt

@@ -21,6 +21,7 @@ import com.amazon.ion.system.IonSystemBuilder
 import com.amazon.ionelement.api.MetaContainer
 import com.amazon.ionelement.api.emptyMetaContainer
 import com.amazon.ionelement.api.toIonValue
+import org.partiql.lang.ast.IsOrderedMeta
 import org.partiql.lang.ast.SourceLocationMeta
 import org.partiql.lang.ast.UNKNOWN_SOURCE_LOCATION
 import org.partiql.lang.ast.sourceLocation
@@ -261,34 +262,25 @@ internal class PhysicalPlanCompilerImpl(
         val mapThunk = compileAstExpr(expr.exp)
         val bexprThunk: RelationThunkEnv = bexperConverter.convert(expr.query)
 
-        fun createOutputSequence(relationType: RelationType?, elements: Sequence<ExprValue>) = when (relationType) {
-            RelationType.LIST -> ExprValue.newList(elements)
-            RelationType.BAG -> ExprValue.newBag(elements)
-            null -> throw EvaluationException(
-                message = "Unable to recover the output Relation Type",
-                errorCode = ErrorCode.EVALUATOR_GENERIC_EXCEPTION,
-                internal = false
-            )
+        val relationType = when (expr.metas.containsKey(IsOrderedMeta.tag)) {
+            true -> RelationType.LIST
+            false -> RelationType.BAG
         }
 
         return thunkFactory.thunkEnv(expr.metas) { env ->
-            var relationType: RelationType? = null
             // we create a snapshot for currentRegister to use during the evaluation
             // this is to avoid issue when iterator planner result
             val currentRegister = env.registers.clone()
             val elements = sequence {
                 env.load(currentRegister)
                 val relItr = bexprThunk(env)
-                relationType = relItr.relType
                 while (relItr.nextRow()) {
                     yield(mapThunk(env))
                 }
             }
-
-            // Trick the compiler here to always initialize `relationType`
-            when (elements.firstOrNull()) {
-                null -> createOutputSequence(relationType, emptySequence())
-                else -> createOutputSequence(relationType, elements)
+            when (relationType) {
+                RelationType.LIST -> ExprValue.newList(elements)
+                RelationType.BAG -> ExprValue.newBag(elements)
             }
         }
     }

lang/src/main/kotlin/org/partiql/lang/eval/visitors/AggregationVisitorTransform.kt

@@ -105,7 +105,7 @@ internal class AggregationVisitorTransform(
 
     override fun transformExprSelect_group(node: PartiqlAst.Expr.Select): PartiqlAst.GroupBy? {
         // Return with Empty Context if without Group
-        val containsAggregations = AggregationFinder.containsAggregations(node.project)
+        val containsAggregations = AggregationFinder().containsAggregations(node.project)
         if (node.group == null) {
             val context = VisitorContext(emptyList(), null, containsAggregations)
             contextStack.add(context)
@@ -202,7 +202,8 @@ internal class AggregationVisitorTransform(
      * Recursively searches through a [PartiqlAst.Projection] to find [PartiqlAst.Expr.CallAgg]'s, but does NOT recurse
      * into [PartiqlAst.Expr.Select]. Designed to be called directly using [containsAggregations].
      */
-    private object AggregationFinder : PartiqlAst.Visitor() {
+    private class AggregationFinder : PartiqlAst.Visitor() {
+
         var hasAggregations: Boolean = false
 
         fun containsAggregations(node: PartiqlAst.Projection): Boolean {
@@ -276,7 +277,7 @@ internal class AggregationVisitorTransform(
         }
 
         /**
-         * IDs outside of aggregation functions should always be replaced with the Group Key uniue aliases. If no
+         * IDs outside of aggregation functions should always be replaced with the Group Key unique aliases. If no
          * replacement is found, we throw an EvaluationException.
          */
         private fun getReplacementForIdOutsideOfAggregationFunction(node: PartiqlAst.Expr.Id): PartiqlAst.Expr {

lang/src/main/kotlin/org/partiql/lang/planner/transforms/AstToLogicalVisitorTransform.kt

@@ -3,9 +3,11 @@ package org.partiql.lang.planner.transforms
 import com.amazon.ionelement.api.emptyMetaContainer
 import com.amazon.ionelement.api.ionString
 import com.amazon.ionelement.api.ionSymbol
+import org.partiql.lang.ast.IsOrderedMeta
 import org.partiql.lang.domains.PartiqlAst
 import org.partiql.lang.domains.PartiqlAstToPartiqlLogicalVisitorTransform
 import org.partiql.lang.domains.PartiqlLogical
+import org.partiql.lang.domains.metaContainerOf
 import org.partiql.lang.errors.Problem
 import org.partiql.lang.errors.ProblemHandler
 import org.partiql.lang.eval.builtins.CollectionAggregationFunction
@@ -263,20 +265,25 @@ internal class AstToLogicalVisitorTransform(
     }
 
     private fun transformProjection(node: PartiqlAst.Expr.Select, algebra: PartiqlLogical.Bexpr): PartiqlLogical.Expr {
+        val project = node.project
+        val metas = when (node.order) {
+            null -> project.metas
+            else -> project.metas + metaContainerOf(IsOrderedMeta)
+        }
         return PartiqlLogical.build {
-            when (val project = node.project) {
+            when (project) {
                 is PartiqlAst.Projection.ProjectValue -> {
                     bindingsToValues(
                         exp = transformExpr(project.value),
                         query = algebra,
-                        metas = project.metas
+                        metas = metas
                     )
                 }
                 is PartiqlAst.Projection.ProjectList -> {
                     bindingsToValues(
                         exp = transformProjectList(project),
                         query = algebra,
-                        metas = project.metas
+                        metas = metas
                     )
                 }
                 is PartiqlAst.Projection.ProjectStar -> {
@@ -289,7 +296,7 @@ internal class AstToLogicalVisitorTransform(
                         input = algebra,
                         key = transformExpr(project.key),
                         value = transformExpr(project.value),
-                        metas = project.metas
+                        metas = metas
                     )
                 }
             }

lang/src/test/kotlin/org/partiql/lang/compiler/memorydb/operators/GetByKeyProjectRelationalOperatorFactory.kt

@@ -57,11 +57,17 @@ class GetByKeyProjectRelationalOperatorFactory : ProjectRelationalOperatorFactor
         // Parse the tableId so we don't have to at evaluation-time
         val tableId = UUID.fromString(impl.staticArgs.single().textValue)
 
+        var exhausted = false
+
         // Finally, return a RelationExpression which evaluates the key value expression and returns a
         // RelationIterator containing a single row corresponding to the key (or no rows if nothing matches)
         return RelationExpression { state ->
             // this code runs at evaluation-time.
 
+            if (exhausted) {
+                throw IllegalStateException("Exhausted result set")
+            }
+
             // Get the current database from the EvaluationSession context.
             // Please note that the state.session.context map is immutable, therefore it is not possible
             // for custom operators or functions to put stuff in there. (Hopefully that will reduce the
@@ -74,6 +80,8 @@ class GetByKeyProjectRelationalOperatorFactory : ProjectRelationalOperatorFactor
             // get the record requested.
             val record = db.getRecordByKey(tableId, keyValue)
 
+            exhausted = true
+
             // if the record was not found, return an empty relation:
             if (record == null)
                 relation(RelationType.BAG) {

lang/src/test/kotlin/org/partiql/lang/eval/EvaluatingCompilerCollectionAggregationsTest.kt

@@ -172,8 +172,8 @@ internal class EvaluatingCompilerCollectionAggregationsTest : EvaluatorTestBase(
                 """,
                 expectedResult = """
                     <<
-                        {'k': [2, 4], 'coll_sum_a': 6, 'coll_sum_inner': <<6>>, 'sum_b': 30},
-                        {'k': [6, 7], 'coll_sum_a': 13, 'coll_sum_inner': <<13>>, 'sum_b': 20}
+                        {'k': [2, 4], 'coll_sum_a': 6, 'sum_b': 30,  'coll_sum_inner': <<6>>},
+                        {'k': [6, 7], 'coll_sum_a': 13,  'sum_b': 20, 'coll_sum_inner': <<13>>}
                     >>
                 """
             ),