How to limit # of simultaneous users per account

Srini9009

I am making a datamodel for a website that I am building. I need to limit the # of users who can simultanueosly login to an account to either 1 or 2 depending on the package chosen by the customer.

How do I datamodel the tables to achieve this functionality and how to I design my application for this?

Any help is greatly appreciated.

Thanks,
Srini

bradgrafelman

One way might be to generate some sort of randomized hash value when you succesfully authenticate a user. You'd store that value in your DB and then ensure that it is propagated throughout all of the user's subsequent requests (via cookie, the query string, etc.).

Limiting the number of simultaneous users then just becomes an issue of limiting how many hash values your DB stores for a particular user; if you authenticate a user who already has the maximum number of hash values stored in the DB, you'd replace the oldest stored value with the newly generated one.

NogDog

You might want to include a timestamp with those hash entries which you update to NOW() on each access, so that you can define currently being used as one whose last timestamp was within X minutes ago.

Sxooter

So are you talking about limited them on the front end (aka a web service) or limiting the connections to the database? To limit connections to a database is usually quite dependent on the particular database. In PostgreSQL you can limit connections for a user with the alter user command:

\h alter user
Command: ALTER USER
Description: change a database role
Syntax:
ALTER USER name [ [ WITH ] option [ ... ] ]

where option can be:
(SNIP)
| CONNECTION LIMIT connlimit
(SNIP)

And just set the connection limit right there.

Sxooter

\h alter user
Command: ALTER USER
Description: change a database role
Syntax:
ALTER USER name [ [ WITH ] option [ ... ] ]

where option can be:
(SNIP)
| CONNECTION LIMIT connlimit
(SNIP)

And just set the connection limit right there.