pgsql database group ownership for client databases

ISP solution, we want to allow large email quotas, but report overall disk usage
by a particular user group. for example...

client group is "mygroup"
"mygroup" has a soft quota of 200mb and hard of 250mb
"mygroup" also has two dabases mydb1 and mydb2
we want to include the usage of database files in the usage quota.

this could be simply accomplished by
chown pgsql:mygroup /usr/local/pgsql/data/base/mydb1
chown pgsql:mygroup /usr/local/pgsql/data/base/mydb2

as it doesn't appear that pgsql (the default group for these directories) has
any group permission bits set anyway. This would allow a quota check on the
/usr partition to include any databases storage used by the two databases

I do not believe that this would cause database storage and modification errors
since the pgsql user still has the ability to write into the directories
regardless of mygroup's quota status...

anyone care to sanity check this process for me?

Thanks

Dave