Method decompose

src/dsql/BoolNodes.cpp:1342–1398

}

BoolExprNode* InListBoolNode::decompose(CompilerScratch* csb)
{
	// Search for list items depending on record streams.
	// If found, decompose expression:
	//   <arg> IN (<item1>, <item2>, <item3>, <item4> ...)
	// into:
	//   <arg> IN (<item1>, <item2>, ...) OR <arg> = <item3> OR <arg> = <item4> ...
	// where the ORed booleans are known to be stream-based (i.e. contain fields inside)
	// and thus could use an index, if possible.
	//
	// See #8109 in the tracker, example:
	//
	// SELECT e.*
	// FROM Employees e
	// WHERE :SomeID IN (e.LeaderID, e.DispEmpID)

	auto& pool = csb->csb_pool;
	BoolExprNode* boolNode = nullptr;

	for (auto iter = list->items.begin(); iter != list->items.end();)
	{
		ValueExprNode* const item = *iter;

		SortedStreamList streams;
		item->collectStreams(streams);

		if (streams.isEmpty())
		{
			iter++;
			continue;
		}

		list->items.remove(iter);

		const auto cmpNode = FB_NEW_POOL(pool) ComparativeBoolNode(pool, blr_eql, arg, item);

		if (boolNode)
			boolNode = FB_NEW_POOL(pool) BinaryBoolNode(pool, blr_or, boolNode, cmpNode);
		else
			boolNode = cmpNode;
	}

	if (boolNode && list->items.hasData())
	{
		BoolExprNode* priorNode = this;

		if (list->items.getCount() == 1)
		{
			// Convert A IN (B) into A = B
			priorNode = FB_NEW_POOL(pool) ComparativeBoolNode(pool, blr_eql, arg, list->items.front());
		}

		boolNode = FB_NEW_POOL(pool) BinaryBoolNode(pool, blr_or, boolNode, priorNode);
	}

	return boolNode;
}