Do not fold join conditions from nested loop to outer source

Fixes #548
MarkMpn · Sep 14, 2024 · fd94f86 · fd94f86
1 parent 1028992
commit fd94f86
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Showing 2 changed files with 39 additions and 3 deletions.
diff --git a/MarkMpn.Sql4Cds.Engine.Tests/ExecutionPlanTests.cs b/MarkMpn.Sql4Cds.Engine.Tests/ExecutionPlanTests.cs
@@ -8463,6 +8463,7 @@ OUTER APPLY (
 
             var select = AssertNode<SelectNode>(plans[0]);
             var apply = AssertNode<NestedLoopNode>(select.Source);
+            Assert.AreEqual(QualifiedJoinType.Inner, apply.JoinType);
             var join = AssertNode<MergeJoinNode>(apply.LeftSource);
             var fetch1 = AssertNode<FetchXmlScan>(join.LeftSource);
             var sort = AssertNode<SortNode>(join.RightSource);
@@ -8472,5 +8473,37 @@ OUTER APPLY (
             var compute = AssertNode<ComputeScalarNode>(filter.Source);
             var constant = AssertNode<ConstantScanNode>(compute.Source);
         }
+
+        [TestMethod]
+        public void FilterOnOuterApply()
+        {
+            // https://github.com/MarkMpn/Sql4Cds/issues/548
+            var planBuilder = new ExecutionPlanBuilder(_localDataSources.Values, this);
+
+            var query = @"
+SELECT *
+FROM (
+    SELECT a.accountid,
+           a.name
+    FROM   account a) AS q1
+OUTER APPLY (
+    SELECT IIF(q1.name = 'Test1', 1, 0) AS [flag1],
+           IIF(q1.name = 'Test2', 1, 0) AS [flag2]
+) AS q2
+WHERE q2.flag1 = 1 OR q2.flag2 = 1";
+
+            var plans = planBuilder.Build(query, null, out _);
+
+            Assert.AreEqual(1, plans.Length);
+
+            var select = AssertNode<SelectNode>(plans[0]);
+            var apply = AssertNode<NestedLoopNode>(select.Source);
+            Assert.AreEqual(QualifiedJoinType.LeftOuter, apply.JoinType);
+            Assert.AreEqual("q2.flag1 = 1 OR q2.flag2 = 1", apply.JoinCondition.ToSql());
+            var fetch = AssertNode<FetchXmlScan>(apply.LeftSource);
+            var alias = AssertNode<AliasNode>(apply.RightSource);
+            var compute = AssertNode<ComputeScalarNode>(alias.Source);
+            var constant = AssertNode<ConstantScanNode>(compute.Source);
+        }
     }
 }
diff --git a/MarkMpn.Sql4Cds.Engine/ExecutionPlan/NestedLoopNode.cs b/MarkMpn.Sql4Cds.Engine/ExecutionPlan/NestedLoopNode.cs
@@ -193,8 +193,9 @@ public override IDataExecutionPlanNodeInternal FoldQuery(NodeCompilationContext
                 var joinColumns = JoinCondition.GetColumns().ToList();
                 var hasLeftColumn = joinColumns.Any(c => leftSchema.ContainsColumn(c, out _));
                 var hasRightColumn = joinColumns.Any(c => rightSchema.ContainsColumn(c, out _));
+                var foldedFilter = false;
 
-                if (!hasLeftColumn)
+                if (!hasLeftColumn && JoinType == QualifiedJoinType.Inner)
                 {
                     // Join condition doesn't reference columns from the left source, so we can remove it from the join
                     // and apply it as a filter to the right source. Inner source will often have a table spool - add the filter
@@ -206,17 +207,19 @@ public override IDataExecutionPlanNodeInternal FoldQuery(NodeCompilationContext
 
                     RightSource = RightSource.FoldQuery(innerContext, hints);
                     RightSource.Parent = this;
+                    foldedFilter = true;
                 }
 
-                if (!hasRightColumn)
+                if (!hasRightColumn && (JoinType == QualifiedJoinType.Inner || JoinType == QualifiedJoinType.LeftOuter))
                 {
                     // Join condition doesn't reference columns from the right source, so we can remove it from the join
                     // and apply it as a filter to the left source
                     LeftSource = new FilterNode { Source = LeftSource, Filter = JoinCondition }.FoldQuery(context, hints);
                     LeftSource.Parent = this;
+                    foldedFilter = true;
                 }
 
-                if (!hasLeftColumn || !hasRightColumn)
+                if (foldedFilter)
                     JoinCondition = null;
             }