Best way to handle concurrency issues

Question

i have a LAPP (linux, apache, postgresql and php) environment, but the question is pretty the same both on Postgres or Mysql.

I have an cms app i developed, that handle

Answer 1

Polling is rarely a nice solution.
You could do the timstamp check only when the user (with the open document) is doing something active with the document like scrolling, moving the mouse over it or starts to edit. Then the user gets an alert if the document has been changed.

.....
I know it was not what you asked for but ... why not a edit-singleton?
The singleton could be a userID column in the document-table.
If a user wants to edit the document, the document is locked for edit by other users.

Or have edit-singletons on the individual fields/groups of information.

Only one user can edit the document at a time. If another user has the document open and want to edit a single timestamp check reveal that the document has been altered and is reloaded.

With a singleton there is no polling and only one timestamp check when the user "touches" and/or wants to edit the document.

But perhaps a singleton mechanism doesn't fit your system.

Regards
   Sigersted