What it is
A property of an operation: running it again does not change the result. Confirm pressed twice, a repeated webhook, the same file uploaded again โ no duplicate appears.
How we use it
In Tech Poly VPN a payment is confirmed under a row lock in the database: the second administrator sees who already processed the request, and the subscription is not extended twice. The Joomla import can be re-run without duplicates, and uploading the same statement to the finance assistant again changes nothing.
Where it helps a business
- Two administrators pressed Confirm on the same payment at the same moment.
- A service sent the same event twice.
- A user uploaded the same statement again, or an import had to be re-run.
How we use it
- Payments. In Tech Poly VPN the bot opens a transaction, reads the payment with a row lock and checks its status. If it is no longer pending, the transaction rolls back and the administrator sees who processed the request and when. The race is excluded at the database level, not by an agreement.
- Double-confirmation protection also exists in the subscription-sales bot, where a receipt goes to several admins at once.
- Import. The Joomla to WordPress migration can be re-run: a repeat updates posts but creates no copies, and pages assembled by hand are not overwritten.
- Statements. In the finance assistant uploading the same file again changes nothing, and overlapping periods are reconciled without duplicates.
Common problems
- "We agreed only one person presses it." An agreement between people does not protect against simultaneous clicks; a database lock does.
- Similar but different operations. Two different expenses of the same amount on the same day may merge; in the finance assistant a button separates them.
When you do not need it
Operations that change nothing, such as showing a list or opening a card, are safe to repeat by nature.