Function gen_plan

src/dsql/gen.cpp:437–512

Generate blr for an access plan expression.

// Generate blr for an access plan expression.
static void gen_plan(DsqlCompilerScratch* dsqlScratch, const PlanNode* planNode)
{
	// stuff the join type

	const Array<NestConst<PlanNode> >& list = planNode->subNodes;

	if (list.getCount() > 1)
	{
		dsqlScratch->appendUChar(blr_join);
		dsqlScratch->appendUChar(list.getCount());
	}

	// stuff one or more plan items

	for (const NestConst<PlanNode>* ptr = list.begin(); ptr != list.end(); ++ptr)
	{
		const PlanNode* node = *ptr;

		if (node->subNodes.hasData())
		{
			gen_plan(dsqlScratch, node);
			continue;
		}

		// if we're here, it must be a nod_plan_item

		dsqlScratch->appendUChar(blr_retrieve);

		// stuff the relation -- the relation id itself is redundant except
		// when there is a need to differentiate the base tables of views

		// ASF: node->recordSourceNode may be NULL, and then a BLR error will happen.
		// Example command: select * from (select * from t1) a plan (a natural);
		if (node->recordSourceNode)
			node->recordSourceNode->genBlr(dsqlScratch);

		// now stuff the access method for this stream

		ObjectsArray<PlanNode::AccessItem>::const_iterator idx_iter =
			node->accessType->items.begin();
		FB_SIZE_T idx_count = node->accessType->items.getCount();

		switch (node->accessType->type)
		{
			case PlanNode::AccessType::TYPE_SEQUENTIAL:
				dsqlScratch->appendUChar(blr_sequential);
				break;

			case PlanNode::AccessType::TYPE_NAVIGATIONAL:
				dsqlScratch->appendUChar(blr_navigational);
				dsqlScratch->appendNullString(idx_iter->indexName.c_str());
				if (idx_count == 1)
					break;
				// dimitr: FALL INTO, if the plan item is ORDER ... INDEX (...)
				// ASF: The first item of a TYPE_NAVIGATIONAL is not for blr_indices.
				++idx_iter;
				--idx_count;