Functional requirements
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There are about 55 million items in the Shanghai library.
Annual book circulation volume exceeded 60 million copies in 2015 (http://www.shanghai.gov.cn/nw2/nw2314/nw2315/nw5827/u21aw1103363.html). Taking into account 8% annual growth, the circulation volume by the end to 2020 should be about 84 million copies.
It means that there will be 84 million records in the Audit log for Loan "Check in" events only and approximately the same amount for "Check out" events.
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