A method and associated systems for optimized deduplication of a database stored on multiple tiers of storage devices. A database-deduplication system, upon receiving a request to update a database record, uses memory-resident logs and previously generated database-maintenance tables to identify a first logical block that identifies an updated value, stored in a first physical block of storage, to be used to update a database record and to further identify a second logical block that stores in the database a corresponding existing value of the same record. After determining that the first and second logical blocks reside within the same storage tier, the system directs a deduplication module to associate both logical blocks with the first physical block.
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