Strategy for tracking user recent activity
I wonder how a site like stackoverflow does it?
They must target a specific event, as I just tooled around the site, take a look at my profile, and still says something like last seen 8 minutes ago.
I've seen strategy 1 work before. Of course the site was a small one.
Our solution is to maintain a "Transaction" table (which follows what was done), in addition to our "Session" table (which follows who was here). UPDATE, INSERT and DELETE instructions are all managed through a "Transaction" object and each of these SQL instruction is stored in the "Transaction" table once it has been successfully executed on the database (depending on tables updated: we have the possibility to specifically follow some tables and ignore others). This "Transaction" table has other fields such as transactiontType (I for INSERT, D for DELETE, U for UPDATE), transactionDateTime, etc, and a foreign key "sessionId", telling us finally who sent the instruction. It is even possible, through some code, to identify who did what and when (Gus created the record on monday, Tim changed the Unit Price on tuesday, Liz added an extra discount on thursday, etc).
Pros for this solution are:
- you're able to tell "what who and when", and to show it to your users! (you'll need some code to analyse SQL statements)
- if your data is replicated, and replication fails, you can rebuild your database through this table
Cons are
- 100 000 data updates per month mean 100 000 records in Tbl_Transaction
- Finally, this table tends to be 99% of your database volume
Our choice: all records older than 90 days are automatically deleted every morning