ACCESSING AN EXTERNAL TABLE IN PARALLEL TO EXECUTE A QUERY

摘要

An approach, referred to herein as parallelized-external-table access, generates rows from a single external table in parallel for a given query. Under parallelized-external-table access, an execution plan generated for the query includes multiple work granules that generate rows for a single external table from a data source. Such work granules are referred to herein as external work granules. Each external work granule of the execution plan may be assigned to a slave process, which executes the external work granule in parallel with another slave process executing another external work granule. External tables are accessible on a cluster of data nodes in a distributed data access system (e.g. Hadoop Distributed File System) connected to a DBMS.

主权项

1. A method, comprising:
a DBMS generating an execution plan for a query that requires access to an external table, wherein generating said execution plan includes generating a plurality of external work granules for generating rows for the external table from a data source; and said DBMS executing said execution plan, wherein executing said execution plan comprises a plurality of slave processes executing said external work granules.