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Transactions and Concurrency Control

In the old days when we lived in caves and used mainframe computers with batch file systems, transaction processing was easy. You batched up the transactions to be made against the master file into a transaction file. The transaction file was sorted, edited, and ready to go when you ran it against the master file from a tape drive. The output of this process became the new master file and the old master file and the transaction files were logged to magnetic tape in a huge closet in the basement of the company.

When disk drives, multiuser systems, and databases came along, things got complex and SQL made it more so. But mercifully the user does not have to see the details. Well, here is the first layer of ...

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