SYSTEM AND METHOD FOR FETCHING THE LATEST VERSIONS OF STORED DATA OBJECTS

摘要

A distributed storage system may store data object instances in persistent storage and may cache keymap information for those data object instances. The system may cache a latest symbolic key entry for some user keys of the data object instances. When a request is made for the latest version of stored data object instances having a specified user key, the latest version may be determined dependent on whether a latest symbolic key entry exists for the specified user key, and keymap information for the latest version may be returned. When storing keymap information, a flag may be set to indicate that a corresponding latest symbolic key entry should be updated. The system may delete a latest symbolic key entry for a particular user key from the cache in response to determining that no other requests involving the keymap information for data object instances having the particular user key are pending.

主权项

1. A method, comprising:
performing, by a computer system that stores a plurality of data objects in a distributed storage system:
receiving a request to store an instance of a data object in the distributed storage system, wherein the request comprises a user key for the data object and a version identifier for the instance of the data object;generating keymap information for the instance of the data object that maps the user key to a locator and the locator to the instance of the data object;caching the keymap information at a keymap coordinator in the distributed storage system;caching a latest symbolic key entry at the keymap coordinator, wherein the latest symbolic key entry comprises the version identifier for the instance of the data object and indicates that the instance of the data object is the latest version of the data object stored in the distributed storage system;receiving a request to retrieve the latest version of the data object, wherein the request comprises the user key for the data object but does not include a version identifier of the latest version of the data object;determining the version identifier of the latest version of the data object dependent on the cached latest symbolic key entry; andreturning keymap information for the latest version of the data object.