1. A database-deduplication optimizer comprising one or more processors, one or more memories coupled to the one or more processors, and one or more computer-readable hardware storage devices coupled to the one or more processors, wherein one or more of the computer-readable hardware storage devices contains program code configured to be run by one or more of the processors via one or more of the memories to implement a method for optimizing deduplication of a database that is stored on a set of database storage devices organized into two or more tiers, the method comprising: the database-deduplication optimizer retrieving a transaction request from a database log, wherein the transaction request identifies: an existing record stored in the database; a type of transaction to be performed upon the existing record; and an updated data value to be written to the existing record; the database-deduplication optimizer, in response to the retrieving, identifying a first logical block that corresponds to a first physical block and that stores the updated data value identified by the transaction request; the database-deduplication optimizer further identifying a second logical block that stores, on a storage device of the set of database storage devices, an existing data value comprised by the existing record; and the database-deduplication optimizer directing a deduplication module to associate the first logical block and the second logical block with a same physical block.