Two clerks open the same stock record showing 100 laptops. One records 10 issued and saves 90; the other records 5 issued and saves 95. The stock now shows 95. What happened, and how is it prevented?
Deux agents ouvrent la même fiche de stock indiquant 100 portables. L'un enregistre 10 sorties et sauvegarde 90 ; l'autre enregistre 5 sorties et sauvegarde 95. Le stock indique maintenant 95. Que s'est-il passé, et comment l'éviter ?
Answers
AA dirty read, prevented by adding an index on the stock quantity columnUne lecture sale, évitée en ajoutant un index sur la colonne des quantités en stock
BA lost update, prevented by locking the row or using a version checkUne mise à jour perdue, évitée en verrouillant la ligne ou en utilisant un contrôle de version
CA deadlock, prevented by a bigger serverUn interblocage, évité par un serveur plus puissant
DNothing is wrong; 95 is correctRien d'anormal ; 95 est correct
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