This should fix CORE-6440: expression indices with COALESCE cannot be matched

dyemanov · dyemanov · commit 350aa6f2d55d · 2020-11-16T19:58:55.000+03:00
diff --git a/src/dsql/ExprNodes.cpp b/src/dsql/ExprNodes.cpp
@@ -70,6 +70,28 @@ using namespace Jrd;
 
 namespace
 {
+	bool sameNodes(CompilerScratch* csb, const ValueIfNode* node1,
+				   const CoalesceNode* node2, bool ignoreStreams)
+	{
+		// dimitr:	COALESCE could be represented as ValueIfNode in older databases,
+		// 			so compare them for actually being the same thing:
+		//			COALESCE(A, B) == VALUE_IF(A IS NULL, B, A)
+
+		if (node1 && node2)
+		{
+			const auto missing = nodeAs<MissingBoolNode>(node1->condition);
+			if (missing && missing->arg->sameAs(csb, node1->falseValue, false) &&
+				node2->args->items.getCount() == 2 &&
+				node2->args->items[0]->sameAs(csb, node1->falseValue, ignoreStreams) &&
+				node2->args->items[1]->sameAs(csb, node1->trueValue, ignoreStreams))
+			{
+				return true;
+			}
+		}
+
+		return false;
+	}
+
 	// Try to expand the given stream. If it's a view reference, collect its base streams
 	// (the ones directly residing in the FROM clause) and recurse.
 	void expandViewStreams(CompilerScratch* csb, StreamType baseStream, SortedStreamList& streams)
@@ -3692,6 +3714,14 @@ ValueExprNode* CoalesceNode::copy(thread_db* tdbb, NodeCopier& copier) const
 	return node;
 }
 
+bool CoalesceNode::sameAs(CompilerScratch* csb, const ExprNode* other, bool ignoreStreams) const
+{
+	if (ExprNode::sameAs(csb, other, ignoreStreams))
+		return true;
+
+	return sameNodes(csb, nodeAs<ValueIfNode>(other), this, ignoreStreams);
+}
+
 ValueExprNode* CoalesceNode::pass2(thread_db* tdbb, CompilerScratch* csb)
 {
 	ValueExprNode::pass2(tdbb, csb);
@@ -13373,6 +13403,14 @@ ValueExprNode* ValueIfNode::copy(thread_db* tdbb, NodeCopier& copier) const
 	return node;
 }
 
+bool ValueIfNode::sameAs(CompilerScratch* csb, const ExprNode* other, bool ignoreStreams) const
+{
+	if (ExprNode::sameAs(csb, other, ignoreStreams))
+		return true;
+
+	return sameNodes(csb, this, nodeAs<CoalesceNode>(other), ignoreStreams);
+}
+
 ValueExprNode* ValueIfNode::pass2(thread_db* tdbb, CompilerScratch* csb)
 {
 	ValueExprNode::pass2(tdbb, csb);
diff --git a/src/dsql/ExprNodes.h b/src/dsql/ExprNodes.h
@@ -308,6 +308,7 @@ class CoalesceNode : public TypedNode<ValueExprNode, ExprNode::TYPE_COALESCE>
 
 	virtual void getDesc(thread_db* tdbb, CompilerScratch* csb, dsc* desc);
 	virtual ValueExprNode* copy(thread_db* tdbb, NodeCopier& copier) const;
+	virtual bool sameAs(CompilerScratch* csb, const ExprNode* other, bool ignoreStreams) const;
 	virtual ValueExprNode* pass2(thread_db* tdbb, CompilerScratch* csb);
 	virtual dsc* execute(thread_db* tdbb, jrd_req* request) const;
 
@@ -2150,6 +2151,7 @@ class ValueIfNode : public TypedNode<ValueExprNode, ExprNode::TYPE_VALUE_IF>
 
 	virtual void getDesc(thread_db* tdbb, CompilerScratch* csb, dsc* desc);
 	virtual ValueExprNode* copy(thread_db* tdbb, NodeCopier& copier) const;
+	virtual bool sameAs(CompilerScratch* csb, const ExprNode* other, bool ignoreStreams) const;
 	virtual ValueExprNode* pass2(thread_db* tdbb, CompilerScratch* csb);
 	virtual dsc* execute(thread_db* tdbb, jrd_req* request) const;
 
