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Seat Availability
1 plane/sec · 150 psgr/plane · 100 search/psgr · 1000 fl/search = 15,000,000 availability questions per second
- airline computers can’t support this load
- airline networks can’t support this load
- ITA Software uses distributed, scalable cache
Airline would like to take more features of trip into account
- all flights; all passengers; total price; etc
- would be disastrous for search: too many questions to ask
No locking: answer is not guaranteed for any period of time
- between search and purchase, availability may have changed
Notes:
Another interesting aspect of seat availability is the number of questions that the airlines must answer. If every passenger poses 100 searches before buying a ticket (a number in line with actual behavior) and each search looks at 1,000 flights, then the airlines would need to answer 15,000,000 questions a second. Neither their networks nor their computers can handle this, a situation that forced ITA Software to develop a sophisticated seat availability caching system. The problem is aggravated by O&D availability: if the entire trip must be included in each query, something many airlines desire, then search becomes impossible because every potential solution must be independently validated with the airline.
Finally, the airlines’ seat availability infrastructure does not include any locking mechanism, so even if an airline responds that a booking code is available, there is no guarantee that by the time a traveler says “yes, I’d like to buy it” it still will be.