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Abstract

A technique for stabilizing and collecting data in an information storage and retrieval system, referred to as checkpointing, is described. Checkpointing is used to increase the speed of the database during a recovery by only scanning data that the information storage and retrieval system knows is unstable, instead of scanning all the data in the database. Data that is deemed collectable, such as old data or obsolete data, is identified in a non-persistent memory space, such as a cache memory. A data page contained in an initial or first buffer is stored, also in the form of a data page, to a persistent memory type, such as a hard drive or virtual memory. Next, non-collectable data, or data that is to be maintained, in the initial or first buffer is identified. This data is stored in a second buffer. It is then determined whether the non-collectable data is referenced in an object table in the information storage and retrieval system. A first checkpoint flag field in an allocation map in the non-persistent memory area is set. Once the checkpoint flag field is set, the second buffer is flushed to the non-persistent memory type.

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First Claim