src\backend\executor\execMain.c：
void standard_ExecutorStart(QueryDesc *queryDesc, int eflags)
{
  ……
	/*Distribute memory to operators.*/
	if (Gp_role == GP_ROLE_DISPATCH)
	{
		……
			switch(*gp_resmanager_memory_policy)
			{
				case RESMANAGER_MEMORY_POLICY_AUTO:
					PolicyAutoAssignOperatorMemoryKB(queryDesc->plannedstmt,
													 queryDesc->plannedstmt->query_mem);
					break;
				case RESMANAGER_MEMORY_POLICY_EAGER_FREE:
					PolicyEagerFreeAssignOperatorMemoryKB(queryDesc->plannedstmt,
														  queryDesc->plannedstmt->query_mem);
					break;
				default:
					Assert(IsResManagerMemoryPolicyNone());
					break;
			}