Transaction time databases retain and provide access

to prior states of a database. An update “inserts” a new

record while preserving the old version. Immortal DB

builds transaction time database support into a database

engine, not in middleware. It supports as of queries returning

records current at the specified time. It also supports

snapshot isolation concurrency control. Versions are

stamped with the “clock times” of their updating transactions.

The timestamp order agrees with transaction serialization

order. Lazy timestamping propagates timestamps

to transaction updates after commit. Versions are kept in

an integrated storage structure, with historical versions initially

stored with current data. Time-splits of pages permit

large histories to be maintained, and enable time based indexing,

which is essential for high performance historical

queries. Experiments show that Immortal DB introduces

little overhead for accessing recent database states while

providing access to past states.

PDF file

In: ICDE

Publisher: IEEE Computer Society
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