Ticketing, rebuilt

The old flow had six screens between wanting a ticket and having one. None of them were badly built. Every one of them existed because somewhere, at some point, a question had no default.

taps to buy

3

was six screens, eleven taps

median confirm

820ms

p95 at 1.4s

completion

+18%

same traffic, four weeks after

Every screen was a question with a default#

We listed the six screens and next to each one wrote the answer that 90% of buyers gave. Five of the six had one. A screen that asks a question with a 90% answer is not a choice, it is a confirmation — and confirmations belong on the receipt, not in the flow.

What had to move to the server#

Removing a screen usually means the server now has to be right about something. Three cases carried most of it:

1. 01
   The hold happens on tap

   The old flow held a seat when you reached the payment screen. Now it holds on the first tap, for ninety seconds, and releases on abandon. Buyers stopped losing seats between screens, which was the single biggest complaint.

2. 02
   Fees are resolved once

   Fee logic used to run in two places and occasionally disagree by a rappen. It now resolves server-side with the hold and travels with it — the client never computes money.

3. 03
   The account is created after

   We create the account from the payment record once the purchase clears, and email a link to set a password. Nobody has ever been happy to make an account before being allowed to buy something.

Sub-second, and how it is measured#

“Sub-second confirm” means from the tap on Pay to the ticket being on screen and valid at the door — not to a spinner, not to a redirect. The number that mattered was the p95, because the median was already fine and the tail is what people remember.

-- the hold is a row with a deadline; expiry is a query, not a job
select seat_id
from seat_hold
where event_id = $1
  and expires_at > now()
for update skip locked;

skip locked is doing the quiet work there: two buyers reaching for the same seat at the same moment no longer queue behind each other, the second one just gets the next free seat in the same round trip.

What we would do differently#