Function PASS1_derived_table

src/dsql/pass1.cpp:985–1295

Process derived table which is part of a from clause.

// Process derived table which is part of a from clause.
RseNode* PASS1_derived_table(DsqlCompilerScratch* dsqlScratch, SelectExprNode* input,
	const char* cte_alias, const SelectNode* select)
{
	DEV_BLKCHK(dsqlScratch, dsql_type_req);

	thread_db* tdbb = JRD_get_thread_data();
	MemoryPool& pool = *tdbb->getDefaultPool();

	const string& alias = input->alias;

	// Create the context now, because we need to know it for the tables inside.
	dsql_ctx* const context = PASS1_make_context(dsqlScratch, input);

	// Save some values to restore after rse process.
	DsqlContextStack* const req_base = dsqlScratch->context;
	const string aliasRelationPrefix = dsqlScratch->aliasRelationPrefix;

	// Change context, because the derived table cannot reference other streams
	// at the same scope_level (unless this is a lateral derived table).
	DsqlContextStack temp;
	// Put special contexts (NEW/OLD) also on the stack
	for (DsqlContextStack::iterator stack(*dsqlScratch->context); stack.hasData(); ++stack)
	{
		dsql_ctx* local_context = stack.object();

		if ((context->ctx_flags & CTX_lateral) ||
			(local_context->ctx_scope_level < dsqlScratch->scopeLevel) ||
			(local_context->ctx_flags & CTX_system))
		{
			temp.push(local_context);
		}
	}

	dsql_ctx* baseContext = NULL;

	if (temp.hasData())
		baseContext = temp.object();

	dsqlScratch->context = &temp;
	dsqlScratch->aliasRelationPrefix = pass1_alias_concat(aliasRelationPrefix, alias);

	RecordSourceNode* query = input->querySpec;
	UnionSourceNode* unionQuery = nodeAs<UnionSourceNode>(query);
	RseNode* rse = NULL;
	const bool isRecursive = unionQuery && unionQuery->recursive;
	USHORT recursive_map_ctx = 0;

	if (isRecursive)
	{
		// Create dummy, non-recursive select dsqlScratch by doing a union of
		// one, non-recursive member. The dummy will be replaced at the end
		// of this function.

		RecordSourceNode* save = unionQuery->dsqlClauses->items.pop();
		unionQuery->recursive = false;

		dsql_ctx* baseUnionCtx = dsqlScratch->unionContext.hasData() ?
			dsqlScratch->unionContext.object() : NULL;