MIRRORING, IN MEMORY, DATA FROM DISK TO IMPROVE QUERY PERFORMANCE

摘要

Techniques are provided for maintaining data persistently in one format, but making that data available to a database server in more than one format. For example, one of the formats in which the data is made available for query processing is based on the on-disk format, while another of the formats in which the data is made available for query processing is independent of the on-disk format. Data that is in the format that is independent of the disk format may be maintained exclusively in volatile memory to reduce the overhead associated with keeping the data in sync with the on-disk format copies of the data.

主权项

1. A method comprising:
maintaining, on persistent storage, a database that is accessible to a database server; wherein the database includes a first set of data, stored on the persistent storage, in a persistent format; generating a second set of data by converting the first set of data to a mirror format; wherein the mirror format is different from and independent of the persistent format; maintaining the second set of data in volatile memory accessible to the database server; wherein each data item in the second set of data is a copy of a corresponding data item in the first set of data; within the volatile memory, the database server maintaining the second set of data transactionally consistent with the first set of data as the database server executes database operations that make changes to the first set of data.