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

dyemanov · dyemanov · commit 3dc8c2de80ed · 2020-11-11T19:15:46.000+03:00
diff --git a/src/dsql/ExprNodes.cpp b/src/dsql/ExprNodes.cpp
@@ -67,6 +67,27 @@ using namespace Jrd;
 
 namespace
 {
+	bool sameNodes(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 MissingBoolNode* const missing = node1->condition->as<MissingBoolNode>();
+			if (missing && missing->arg->sameAs(node1->falseValue, false) &&
+				node2->args->items.getCount() == 2 &&
+				node2->args->items[0]->sameAs(node1->falseValue, ignoreStreams) &&
+				node2->args->items[1]->sameAs(node1->trueValue, ignoreStreams))
+			{
+				return true;
+			}
+		}
+
+		return false;
+	}
+
 	// Expand DBKEY for view
 	void expandViewNodes(thread_db* tdbb, CompilerScratch* csb, StreamType stream,
 						 ValueExprNodeStack& stack, UCHAR blrOp)
@@ -2988,6 +3009,14 @@ ValueExprNode* CoalesceNode::copy(thread_db* tdbb, NodeCopier& copier) const
 	return node;
 }
 
+bool CoalesceNode::sameAs(const ExprNode* other, bool ignoreStreams) const
+{
+	if (ExprNode::sameAs(other, ignoreStreams))
+		return true;
+
+	return sameNodes(other->as<ValueIfNode>(), this, ignoreStreams);
+}
+
 ValueExprNode* CoalesceNode::pass2(thread_db* tdbb, CompilerScratch* csb)
 {
 	ValueExprNode::pass2(tdbb, csb);
@@ -11738,6 +11767,14 @@ ValueExprNode* ValueIfNode::copy(thread_db* tdbb, NodeCopier& copier) const
 	return node;
 }
 
+bool ValueIfNode::sameAs(const ExprNode* other, bool ignoreStreams) const
+{
+	if (ExprNode::sameAs(other, ignoreStreams))
+		return true;
+
+	return sameNodes(this, other->as<CoalesceNode>(), 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
@@ -220,6 +220,7 @@ 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(const ExprNode* other, bool ignoreStreams) const;
 	virtual ValueExprNode* pass2(thread_db* tdbb, CompilerScratch* csb);
 	virtual dsc* execute(thread_db* tdbb, jrd_req* request) const;
 
@@ -1554,6 +1555,7 @@ 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(const ExprNode* other, bool ignoreStreams) const;
 	virtual ValueExprNode* pass2(thread_db* tdbb, CompilerScratch* csb);
 	virtual dsc* execute(thread_db* tdbb, jrd_req* request) const;
 
