gpfdist:// Protocol

The gpfdist:// protocol is used in a URI to reference a running gpfdist instance.

The gpfdist utility serves external data files from a directory on a file host to all Greenplum Database segments in parallel.

gpfdist is located in the $GPHOME/bin directory on your Greenplum Database master host and on each segment host.

Run gpfdist on the host where the external data files reside. For readable external tables, gpfdist uncompresses gzip (.gz) and bzip2 (.bz2) files automatically. For writable external tables, data is compressed using gzip if the target file has a .gz extension. You can use the wildcard character (*) or other C-style pattern matching to denote multiple files to read. The files specified are assumed to be relative to the directory that you specified when you started the gpfdist instance.

Note: Compression is not supported for readable and writeable external tables when the gpfdist utility runs on Windows platforms.

All primary segments access the external file(s) in parallel, subject to the number of segments set in the gp_external_max_segments server configuration parameter. Use multiple gpfdist data sources in a CREATE EXTERNAL TABLE statement to scale the external table’s scan performance.

gpfdist supports data transformations. You can write a transformation process to convert external data from or to a format that is not directly supported with Greenplum Database external tables.

For more information about configuring gpfdist, see Using the Greenplum Parallel File Server (gpfdist).

See the gpfdist reference documentation for more information about using gpfdist with external tables.

Parent topic: Defining External Tables

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