Registers a custom data access protocol that can be specified when defining a Greenplum Database external table.
CREATE [TRUSTED] PROTOCOL <name> (
[readfunc='<read_call_handler>'] [, writefunc='<write_call_handler>']
[, validatorfunc='<validate_handler>' ])
CREATE PROTOCOL
associates a data access protocol name with call handlers that are responsible for reading from and writing data to an external data source.
The CREATE PROTOCOL
command must specify either a read call handler or a write call handler. The call handlers specified in the CREATE PROTOCOL
command must be defined in the database.
The protocol name can be specified in a CREATE EXTERNAL TABLE
command.
For information about creating and enabling a custom data access protocol, see "Example Custom Data Access Protocol" in the Greenplum Database Administrator Guide.
GRANT
permissions on the protocol to other database roles.
CREATE EXTERNAL TABLE
command.
Greenplum Database handles external tables of type file
, gpfdist
, and gpfdists
internally. The custom protocol gphdfs
(deprecated) is registered in Greenplum Database by default. See Configuring and Using S3 External Tables for information about enabling the S3
protocol. Refer to pxf:// Protocol for information about using the pxf
protocol.
Any shared library that implements a data access protocol must be located in the same location on all Greenplum Database segment hosts. For example, the shared library can be in a location specified by the operating system environment variable LD_LIBRARY_PATH
on all hosts. You can also specify the location when you define the handler function. For example, when you define the s3
protocol in the CREATE PROTOCOL
command, you specify $libdir/gps3ext.so
as the location of the shared object, where $libdir
is located at $GPHOME/lib
.
CREATE PROTOCOL
is a Greenplum Database extension.
ALTER PROTOCOL, CREATE EXTERNAL TABLE, DROP PROTOCOL, GRANT
Parent topic: SQL Command Reference