extproc_perl 2.0 Frequently Asked Questions

There is a CVS repository, but there is no public access yet. It will be opened up for the 2.0 release, however.

As of 1.99_05, you can use the following data types as parameters or return values:

• VARCHAR2
• PLS_INTEGER
• REAL
• NUMBER (cast to PLS_INTEGER or REAL)
• DATE

Planned for a later release of 2.0:

• BLOB
• CLOB
• user defined types

Yes, with DBI callbacks. This is all done using the existing IPC infrastructure between the database and the external procedure, so it's extremely fast and requires no authentication. See the user's guide for details.

Almost. You can use any module that does not load arbitrary shared libraries (modules *linked* with shared libraries are okay). The only module that comes to mind that would be affected by this is Inline, but there may be others.

It's probably an XS module built from C. You need to relink libperlxsi.so before you can use the module. See the user's guide for detailed instructions.

You have to relink when you want to use any XS-based Perl module from extproc_perl. These modules are compiled from C and generate shared objects which are loaded by Perl when you use the module. Unfortunately, Oracle does not allow the dynamic loading of shared objects from external procedures, which prevents these Perl modules from loading. extproc_perl works around this by linking these shared objects into libperlxsi.so, which is in turn linked to extproc_perl.so, the primary extproc_perl library. It also disables DynaLoader, which stops Perl from even trying to load shared objects at runtime. During the relink, stubs are created for each module that makes it look like they are statically linked into Perl. When extproc_perl is started, libperlxsi.so is loaded automatically by the operating system before it passes control back to Oracle. Since the module shared objects are linked to this library, they are loaded as well. Once all dependencies are loaded, control is passed back to Oracle.

The ExtProc module expects to be be run from the interpreter embedded in extproc_perl.so. When it is loaded from the standard Perl binary, it won't find the symbols it is expecting and will die a quick death. If you're using version 1.99_05 or earlier, you need to comment out the use ExtProc; statement to work around this, but your mileage may vary. In versions 1.99_06 and later, preload the extproc_perl.so library by setting the LD_PRELOAD environment variable to the full path to extproc_perl.so and re-run the Perl command. You can do it all on one line as follows (Bourne shell):

LD_PRELOAD=$ORACLE_HOME/lib/extproc_perl.so perl -cw foo.pl

extproc_perl 1.0 only had one shared library. Version 2.0 consists of three shared libraries. Here's what they do:

extproc_perl.so
The core extproc_perl library. This is loaded by Oracle the first time any Perl procedure is called. It is linked to libperlxsi.so.

libperlxsi.so
Contains code to bootstrap Perl XS modules and is linked to all of the Perl module shared objects, including libExtProc.so. This library is responsible for pulling in the module shared objects into extproc_perl before handing control back to Oracle. This is important because Oracle won't let Perl load shared libraries itself. It is separate from extproc_perl.so so modules can be linked in without changing the extproc_perl core.

libExtProc.so
This is the shared object for the ExtProc module.

The include path needs to be set in the configuration file with the inc_path directive. This is a colon separated list of paths. For example:

inc_path=/home/jeff/perl/lib:/tmp/lib

Yes. Rebuilding Perl and all of its dependencies with a 64-bit compiler is not always feasible (or desirable), but fortunately Oracle provides a 32-bit version of the extproc binary called extproc32. You can force Oracle to use it by changing the PROGRAM for the PLSExtProc service in listener.ora:

    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = /u01/app/oracle/product/9.2.0)
      (PROGRAM = extproc32)
    )

Yes. If you're using SQL*Plus, set the SQLPATH environment variable to include the trusted code directory.