Implementation of Delayed Updates in Heraclitus
نویسندگان
چکیده
The Heraclitus languages are database programming languages that give prominence to \delayed updates" or deltas, which are rst-class values representing sets of proposed updates, such as inserts and deletes, to the underlying persistent store. Deltas can be created, inspected and combined without committing to the given updates. Deltas are useful for realizing advanced database features that manipulate virtual database states in addition to the currently stored state; examples include supporting rule-based triggers, hypothetical reasoning, and concurrent transaction processing systems. This paper introduces HeraclitussAlg], a relational algebra extended by deltas, and the HERALD system that implements it. HeraclitussAlg] is a low-level, internal language which will be used in the implementation of richer, calculus-style Heraclitus languages that have been previously proposed. HERALD is built on top of the Wisconsin Storage System (WiSS), and extends this system to support deltas and the various delta operators.
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