Function FetchStatementTargetList

src/backend/tcop/pquery.c:461–525

* FetchStatementTargetList * Given a statement that returns tuples, extract the query targetlist. * Returns NIL if the statement doesn't have a determinable targetlist. * * This can be applied to a Query or a PlannedStmt. * That's more general than portals need, but plancache.c uses this too. * * Note: do not modify the result. * * XXX be careful to keep this in sync with UtilityReturns

 * XXX be careful to keep this in sync with UtilityReturnsTuples.
 */
List *
FetchStatementTargetList(Node *stmt)
{
	if (stmt == NULL)
		return NIL;
	if (IsA(stmt, Query))
	{
		Query	   *query = (Query *) stmt;

		if (query->commandType == CMD_UTILITY)
		{
			/* transfer attention to utility statement */
			stmt = query->utilityStmt;
		}
		else
		{
			if (query->commandType == CMD_SELECT &&
				query->parentStmtType == PARENTSTMTTYPE_NONE)
				return query->targetList;
			if (query->returningList)
				return query->returningList;
			return NIL;
		}
	}
	if (IsA(stmt, PlannedStmt))
	{
		PlannedStmt *pstmt = (PlannedStmt *) stmt;

		if (pstmt->commandType == CMD_UTILITY)
		{
			/* transfer attention to utility statement */
			stmt = pstmt->utilityStmt;
		}
		else
		{
			if (pstmt->commandType == CMD_SELECT &&
				pstmt->intoClause == NULL &&
				pstmt->copyIntoClause == NULL &&
				pstmt->refreshClause == NULL)
				return pstmt->planTree->targetlist;
			if (pstmt->hasReturning)
				return pstmt->planTree->targetlist;
			return NIL;
		}
	}
	if (IsA(stmt, FetchStmt))
	{
		FetchStmt  *fstmt = (FetchStmt *) stmt;
		Portal		subportal;

		Assert(!fstmt->ismove);
		subportal = GetPortalByName(fstmt->portalname);
		Assert(PortalIsValid(subportal));
		return FetchPortalTargetList(subportal);
	}
	if (IsA(stmt, ExecuteStmt))
	{
		ExecuteStmt *estmt = (ExecuteStmt *) stmt;