This paper discusses issues raised by providing disconnected operation in the Thor object-oriented database system. Disconnected operation in such a system poses new challenges because of the small size of objects, the richness and complexity of their interconnections, the huge number of them, and the fact that they are accessed within atomic transactions. We propose three techniques to address these challenges: (1) using the database query language for hoarding; (2) using dependent commits to tentatively commit transactions at the disconnected client; (3) using the high-level semantic of objects to avoid transaction aborts.

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