// Calculate the amount of memory reserved for the query
int64
ResourceManagerGetQueryMemoryLimit(PlannedStmt* stmt)
{
	if (Gp_role != GP_ROLE_DISPATCH)
		return 0;

	/* no limits in single user mode. */
	if (!IsUnderPostmaster)   // 如果是postmaster的子进程，则IsUnderPostmaster为true。
		return 0;

	Assert(gp_session_id > -1);
	Assert(ActivePortal != NULL);

	if (IsResQueueEnabled())
		return ResourceQueueGetQueryMemoryLimit(stmt, ActivePortal->queueId);
	if (IsResGroupActivated())
		return ResourceGroupGetQueryMemoryLimit();

	return 0;
}