1. Installation and Administration Guide
  2. Install and Configure the Database for Oracle Machine Learning for R

2 Install and Configure the Database for Oracle Machine Learning for R

This chapter explains how to install and configure Oracle Database to support OML4R Server.

This chapter contains these topics:

2.1 Install Oracle Database for Oracle Machine Learning for R

Installation instructions for Oracle Database.

OML4R requires the 64-bit version of Oracle Database Enterprise Edition or Standard Edition 2. For the supported platforms, see Oracle Machine Learning for R System Requirements for On-Premises Database.

To install Oracle Database, follow the installation instructions for your supported platform:

  1. Go to the Oracle Database Documentation page in Oracle Help Center.
  2. Select the version of Oracle Database to install.
  3. In the Topics section, select Install and Upgrade.
  4. In the section for your operating system, select the appropriate installation guide.

Note:

You can install OML4R Server in a pluggable database (PDB) within a multitenant container database (CDB). The database may not be installed in the root database in the multitenant environment.

For information about managing a multitenant environment, see Oracle Database Administrator's Guide.

Parent topic: Install and Configure the Database for Oracle Machine Learning for R

2.2 Using EXTPROC with Embedded R Execution

Oracle Database uses an external procedure agent named extproc to support external procedures.

An external procedure is a procedure invoked from a program that is written in a different language. OML4R uses extproc to support embedded R execution.

Parent topic: Install and Configure the Database for Oracle Machine Learning for R

2.2.1 About EXTPROC

When an application invokes an external procedure, Oracle Database starts an extproc agent.

The application uses the network connection established by Oracle Database to pass instructions to the agent for executing the procedure. The agent loads a DLL or shared library, runs the external procedure, and passes back to the application any values returned by the external procedure.

Parent topic: Using EXTPROC with Embedded R Execution

2.2.2 About EXTPROC Configuration for OML4R

OML4R uses the default configuration of extproc.

Note:

When using OML4R with Oracle Database 12c or later, the default extproc configuration is required. It will not work with the listener-based extproc.

The extproc agent is spawned directly by Oracle Database, and no configuration changes are required to either listener.ora or tnsnames.ora. If extproc is configured on the database listener, it overrides the default settings.

For R-3.3.0 on Linux 6, by default, extproc supports external procedure calls if the libraries used are in $ORACLE_HOME/bin or $ORACLE_HOME/lib.

To allow extproc to service any external procedure, set EXTPROC_DLLS to ANY or simply leave it blank (the default).

Enable extproc tracing by doing the following:

  1. To your extproc.ora file, add the following statement:
    SET TRACE_LEVEL=ON
  2. Restart the database.

    Traces for all extproc operations are now recorded in the log files in the $ORACLE_HOME/hs/log directory.

For R-3.3.0 on Linux 6 it is necessary to set LD_LIBRARY_PATH in $ORACLE_HOME/hs/admin/extproc.ora to the location of the R-core-extra RPM so that these libraries are found by the Oracle process running extproc. For example, the default location of the R-core-extra RPM is /usr/lib64/R/port/Linux-X64/lib. The extproc.ora entry for that location should be: 

SET LD_LIBRARY_PATH=/usr/lib64/R/port/Linux-X64/lib

In Linux 7 and later, setting LD_LIBRARY_PATH is not necessary because the required versions of these libraries are native to newer systems.

Note:

A database reboot is needed for changes in extproc.ora to take effect.

See Also:

"Default Configuration for External Procedures" in Oracle Database Net Services Administrator's Guide for details

Parent topic: Using EXTPROC with Embedded R Execution

2.2.3 Troubleshooting EXTPROC

Calling an OML4R embedded R function may result in an error if a database configuration problem exists.

If an attempt to call an OML4R embedded R function results in the following error, then the external procedure did not succeed: 

ORA-28575: unable to open RPC connection to external procedure agent.

This error is often a database configuration problem. It may be caused by any of the following:

  • The OML4R user has not been granted RQADMIN role.

  • The Oracle listener configuration is incorrect, which may occur if the default external procedure configuration (which is recommended) is not being used.

  • Networking layer restrictions or issues exist.

  • Restrictions on external procedure calls are in force.

Parent topic: Using EXTPROC with Embedded R Execution