Optimizing the execution of a query in a multi-database system

摘要

Optimizing the execution of a query in a multi-database system includes identifying a region within a table, the table being referenced in the query. The region is stored on data-storage devices on first and second system databases in the multi-database system. A first access plan for the query is developed, the first access plan comprising accessing the version of the region stored on the first system database. A second access plan for the query is developed, the second access plan comprising accessing the version of the region stored on the second system database. A selection is made between the first access plan and the second access plan to execute the query. The query is executed using the selected access plan to produce a result.

主权项

1. A method, implemented at least partly by one or more processors, for optimizing the execution of a query in a multi-database system comprising a plurality of system databases, the method comprising:
identifying, by the one or more processors, a region within a table, the table being referenced in the query; developing a first access plan for the query, the first access plan comprising accessing a version of the region within the table stored on a first one of the system databases in a first arrangement; developing a second access plan for the query, the second access plan comprising accessing another version of the same region with the same table stored on a second one of the system databases in a second arrangement different than the first arrangement; selecting between the first access plan and the second access plan to execute the query at least based on selecting between the first and second arrangements of the same region within the same table, in response to the query; and executing the selected access plan on the selected system database associated with the selected arrangement of the region within the table being referenced in the query, in response to the query.