Database Reference
In-Depth Information
External tables
External tables in Greenplum refer to those database tables that help Greenplum
Database access data from a source that is outside of the database. We can have
different external tables for different formats. Greenplum supports fast, parallel, as
well as nonparallel data loading and unloading. The external tables act as an inter-
facing point to external data source and give an impression of a local data source to
the accessing function.
File-based data sources are supported by external tables. The following file formats
can be loaded onto external tables:
• Regular file-based source (supports Text, CSV, and XML data formats):
file:// or gpfdist:// protocol
• Web-based file source (supports Text, CSV, OS commands, and scripts):
http:// protocol
• Hadoop-based file source (supports Text and custom/user-defined formats):
gphdfs:// protocol
Following is the syntax for the creation and deletion of readable and writable external
• To create a read-only external table:
(<<file paths>>) | EXECUTE '<<query>>'
FORMAT '<<Format name for example:
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