International Business Machines Corporation

Justin H Hill

Timo J Salo

A technique for creating and using a structured cache to increase the efficiency of reading persistent objects from a database. The structured cache is comprised of an object cache, an associations cache, and a data cache. Data read-ahead is used to retrieve rows from a relational database in advance of an application's need for the data. Entries are created in the data cache and association cache as the rows are processed. The data cache stores data in unstructured binary format, delaying the expense of instantiation until an object is requested by the application. At that time, data is retrieved from the data cache, an object is instantiated from the data, and an entry is created in the object cache. This approach also saves storage space that would be wasted if objects were instantiated upon retrieval, but never used. The association cache stores members of an association, organized by member key within owner key for each association. According to the preferred embodiment, maintaining cache consistency is not required, further increasing the efficiency gains that can be realized using this technique.

Structured cache for persistent objects

A technique for using working set hints and query signatures to optimize the selection and execution of fixed, static services or queries of information from a database, object server, or similar data repository. The working set hints describe how to read ahead when doing a database query, in order to retrieve data in a single database access that a task is likely to need as it continues executing. By storing the working set hints externally from the application code, the hints can be modified as experience is gained about the true working set that is required during use of each task without having to modify and recompile the application itself. Signatures are created and associated with query commands or services. These signatures are compared to the working set hints for a task when the task traverses an association and needs to retrieve data from the data repository. The signature which best matches the task's working set hints is automatically selected, and the query or service associated with this signature is then executed, providing an optimized database retrieval operation.

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Durham, NC, United States of America

Justin H Hill