src/backend/utils/resource_manager/memquota.c：
/*
 * ComputeAvgMemKBForMemIntenseOp
 *    Compute the average memory limit for each memory-intensive operators
 * in a given group.
 *
 * If there is no memory-intensive operators in this group, return 0.
 */
static uint64
ComputeAvgMemKBForMemIntenseOp(OperatorGroupNode *groupNode)
{
	if (groupNode->numMemIntenseOps == 0)
	{
		return 0;
	}

	const uint64 nonMemIntenseOpMemKB = (uint64)(*gp_resmanager_memory_policy_auto_fixed_mem);

	return (((double)groupNode->groupMemKB -
			 (double)groupNode->numNonMemIntenseOps * nonMemIntenseOpMemKB) /
			groupNode->numMemIntenseOps);
}