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Code Editor : README

DB_File

Version 1.830

2 November 2013

Copyright (c) 1995-2013 Paul Marquess. All rights reserved. This
      program is free software; you can redistribute it and/or modify
                  it under the same terms as Perl itself.

IMPORTANT NOTICE
================

If are using the locking technique described in older versions of
DB_File, please read the section called "Locking: The Trouble with fd"
in DB_File.pm immediately. The locking method has been found to be
unsafe. You risk corrupting your data if you continue to use it.

DESCRIPTION
-----------

DB_File is a module which allows Perl programs to make use of the
facilities provided by Berkeley DB version 1. (DB_File can be built
version 2, or greater, of Berkeley DB, but it will only support the 1.x
features).

If you want to make use of the new features available in Berkeley DB
2.x, or greater, use the Perl module BerkeleyDB instead.

Berkeley DB is a C library which provides a consistent interface to a
number of database formats. DB_File provides an interface to all three
of the database types (hash, btree and recno) currently supported by
Berkeley DB.

For further details see the documentation included at the end of the
file DB_File.pm.

PREREQUISITES
-------------

Before you can build DB_File you must have the following installed on
your system:

* Perl 5.004_05 or greater.

* Berkeley DB.

The official web site for Berkeley DB is

http://www.oracle.com/technology/products/berkeley-db/db/index.html

The latest version of Berkeley DB is always available there. It
      is recommended that you use the most recent version available.

The one exception to this advice is where you want to use DB_File
      to access database files created by a third-party application, like
      Sendmail or Netscape. In these cases you must build DB_File with a
      compatible version of Berkeley DB.

If you want to use Berkeley DB 2.x, you must have version 2.3.4
      or greater.  If you want to use Berkeley DB 3.x or 4.x, any version
      will do. For Berkeley DB 1.x, use either version 1.85 or 1.86.

BUILDING THE MODULE
-------------------

Assuming you have met all the prerequisites, building the module should
be relatively straightforward.

Step 1 : If you are running either Solaris 2.5 or HP-UX 10 and want
         to use Berkeley DB version 2, 3 or 4, read either the Solaris Notes
         or HP-UX Notes sections below.  If you are running Linux please
         read the Linux Notes section before proceeding.

Step 2 : Edit the file config.in to suit you local installation.
         Instructions are given in the file.

Step 3 : Build and test the module using this sequence of commands:

perl Makefile.PL
             make
             make test

NOTE:
      If you have a very old version of Berkeley DB (i.e. pre 1.85),
      three of the tests in the recno test harness may fail (tests 51,
      53 and 55). You can safely ignore the errors if you're never
      going to use the broken functionality (recno databases with a
      modified bval).  Otherwise you'll have to upgrade your DB
      library.

INSTALLATION
------------

make install

UPDATES
=======

The most recent version of DB_File is always available at

http://www.cpan.org/modules/by-module/DB_File/

TROUBLESHOOTING
===============

Here are some of the common problems people encounter when building
DB_File.

Missing db.h or libdb.a
-----------------------

If you get an error like this:

cc -c -I/usr/local/include -Dbool=char -DHAS_BOOL
  -O2    -DVERSION=\"1.64\" -DXS_VERSION=\"1.64\" -fpic
  -I/usr/local/lib/perl5/i586-linux/5.00404/CORE -DmDB_Prefix_t=size_t
  -DmDB_Hash_t=u_int32_t DB_File.c
  DB_File.xs:101: db.h: No such file or directory

or this:

LD_RUN_PATH="/lib" cc -o blib/arch/auto/DB_File/DB_File.so  -shared
  -L/usr/local/lib DB_File.o    -L/usr/local/lib -ldb
  ld: cannot open -ldb: No such file or directory

This symptom can imply:

1. You don't have Berkeley DB installed on your system at all.
    Solution: get & install Berkeley DB.

2. You do have Berkeley DB installed, but it isn't in a standard place.
    Solution: Edit config.in and set the LIB and INCLUDE variables to point
              to the directories where libdb.a and db.h are installed.

Undefined symbol db_version
---------------------------

DB_File seems to have built correctly, but you get an error like this
when you run the test harness:

$ make test
  PERL_DL_NONLAZY=1 /usr/bin/perl5.00404 -I./blib/arch -I./blib/lib
  -I/usr/local/lib/perl5/i586-linux/5.00404 -I/usr/local/lib/perl5 -e 'use
  Test::Harness qw(&runtests $verbose); $verbose=0; runtests @ARGV;' t/*.t
  t/db-btree..........Can't load './blib/arch/auto/DB_File/DB_File.so' for
  module DB_File: ./blib/arch/auto/DB_File/DB_File.so: undefined symbol:
  db_version at /usr/local/lib/perl5/i586-linux/5.00404/DynaLoader.pm
  line 166.

at t/db-btree.t line 21
  BEGIN failed--compilation aborted at t/db-btree.t line 21.
  dubious Test returned status 2 (wstat 512, 0x200)

This error usually happens when you have two version of Berkeley DB
installed on your system -- specifically, if you have both version 1 and
a newer version (i.e. version 2 or better) of Berkeley DB installed. If
DB_File is built using the db.h for the newer Berkeley DB and the version
1 Berkeley DB library you will trigger this error. Unfortunately the two
versions aren't compatible with each other. The undefined symbol error is
caused because Berkeley DB version 1 doesn't have the symbol db_version.

Solution: Setting the LIB & INCLUDE variables in config.in to point to the
          correct directories can sometimes be enough to fix this
          problem. If that doesn't work the easiest way to fix the
          problem is to either delete or temporarily rename the copies
          of db.h and libdb.a that you don't want DB_File to use.

Undefined symbol dbopen
-----------------------

DB_File seems to have built correctly, but you get an error like this
when you run the test harness:

...
  t/db-btree..........Can't load 'blib/arch/auto/DB_File/DB_File.so' for
  module DB_File: blib/arch/auto/DB_File/DB_File.so: undefined symbol:
  dbopen at /usr/local/lib/perl5/5.6.1/i586-linux/DynaLoader.pm line 206.
   at t/db-btree.t line 23
  Compilation failed in require at t/db-btree.t line 23.
  ...

This error usually happens when you have both version 1 and a more recent
version of Berkeley DB installed on your system and DB_File attempts
to build using the db.h for Berkeley DB version 1 and the newer version
library. Unfortunately the two versions aren't compatible with each
other. The undefined symbol error is actually caused because versions
of Berkeley DB newer than version 1 doesn't have the symbol dbopen.

Incompatible versions of db.h and libdb
---------------------------------------

DB_File seems to have built correctly, but you get an error like this
when you run the test harness:

$ make test
  PERL_DL_NONLAZY=1 /home/paul/perl/install/bin/perl5.00560 -Iblib/arch
  -Iblib/lib -I/home/paul/perl/install/5.005_60/lib/5.00560/i586-linux
  -I/home/paul/perl/install/5.005_60/lib/5.00560 -e 'use Test::Harness
  qw(&runtests $verbose); $verbose=0; runtests @ARGV;' t/*.t
  t/db-btree..........
  DB_File was build with libdb version 2.3.7
  but you are attempting to run it with libdb version 2.7.5
  BEGIN failed--compilation aborted at t/db-btree.t line 21.
  ...

Another variation on the theme of having two versions of Berkeley DB on
your system.

Keep getting "At least one secondary cursor must be specified to DB->join"
--------------------------------------------------------------------------

When you either run the DB_File test harness, or attempt to run a script
that uses DB_File you get the error message below.

BDB0588 At least one secondary cursor must be specified to DB->join.

To date thus issue has only been reported on Windows. If you encounter this
issue on another platform, please report the issue. See the FEEDBACK
section for details.

This issue boils down to the size of the C type time_t.

The typical reason for getting this error is when running a 32-bit Perl
(which will use a 32-bit time_t) along with a 32-bit Berkeley DB library.
The key point is how Berkeley DB has been built. If it has been built with
a newish version of Visual C++, time_t will default to 64-bit, even when
the rest of the library has been built 32-bit. This means that Perl thinks
time_t is 32-bit, but Berkeley DB thinks it is 64-bit.

More details of how the size of time_t in Windows is shown below (taken
from http://msdn.microsoft.com/en-us/library/w4ddyt9h.aspx)

In versions of Visual C++ and Microsoft C/C++ before Visual C++ 2005,
    time_t was a long int (32 bits) and hence could not be used for dates
    past 3:14:07 January 19, 2038, UTC. time_t is now equivalent to
    __time64_t by default, but defining _USE_32BIT_TIME_T changes time_t
    to __time32_t and forces many time functions to call versions that take
    the 32-bit time_t.

When DB_File is built, it uses a Berkeley DB header file, called db.h. This
file contains the definition of a number of key data structures used by
Berkeley DB. Unfortunately one of those data structures includes a time_t.
This is the root case for this issue. When you build DB_File, it assumes
time_t is 32-bit, but the Berkeley DB library is expecting it to be 64-bit.

Solution:

There are a few options available.

1. Use a 64-bit Perl along with a 64-bit Berkleley DB.

2. Use a 32-bit Perl along with a 32-bit Berkeley DB where _USE_32BIT_TIME_T
   has been defined.

3. If you do need to interoperate with a Berkeley DB library that uses a
   time_t that is different from Perl you need to edit the file DB_File.xs
   and find these lines

/* #define time_t __time64_t */
        /* #define time_t __time32_t */

If your Berkeley DB library uses a 64-bit time_t, uncomment the first line.
    If your Berkeley DB library uses a 32-bit time_t, uncomment the second line.

Solaris build fails with "language optional software package not installed"
---------------------------------------------------------------------------

If you are trying to build this module under Solaris and you get an
error message like this

/usr/ucb/cc: language optional software package not installed

it means that Perl cannot find the C compiler on your system. The cryptic
message is just Sun's way of telling you that you haven't bought their
C compiler.

When you build a Perl module that needs a C compiler, the Perl build
system tries to use the same C compiler that was used to build perl
itself. In this case your Perl binary was built with a C compiler that
lived in /usr/ucb.

To continue with building this module, you need to get a C compiler,
or tell Perl where your C compiler is, if you already have one.

Assuming you have now got a C compiler, what you do next will be dependant
on what C compiler you have installed. If you have just installed Sun's
C compiler, you shouldn't have to do anything. Just try rebuilding
this module.

If you have installed another C compiler, say gcc, you have to tell perl
how to use it instead of /usr/ucb/cc.

This set of options seems to work if you want to use gcc. Your mileage
may vary.

perl Makefile.PL CC=gcc CCCDLFLAGS=-fPIC OPTIMIZE=" "
    make test

If that doesn't work for you, it's time to make changes to the Makefile
by hand. Good luck!

Solaris build fails with "gcc: unrecognized option `-KPIC'"
-----------------------------------------------------------

You are running Solaris and you get an error like this when you try to
build this Perl module

gcc: unrecognized option `-KPIC'

This symptom usually means that you are using a Perl binary that has been
built with the Sun C compiler, but you are using gcc to build this module.

When Perl builds modules that need a C compiler, it will attempt to use
the same C compiler and command line options that was used to build perl
itself. In this case "-KPIC" is a valid option for the Sun C compiler,
but not for gcc. The equivalent option for gcc is "-fPIC".

The solution is either:

1. Build both Perl and this module with the same C compiler, either
       by using the Sun C compiler for both or gcc for both.

2. Try generating the Makefile for this module like this perl

perl Makefile.PL CC=gcc CCCDLFLAGS=-fPIC OPTIMIZE=" " LD=gcc
           make test

This second option seems to work when mixing a Perl binary built
       with the Sun C compiler and this module built with gcc. Your
       mileage may vary.

Linux Notes
-----------

Some older versions of Linux (e.g. RedHat 6, SuSe 6) ship with a C library
that has version 2.x of Berkeley DB linked into it. This makes it
difficult to build this module with anything other than the version of
Berkeley DB that shipped with your Linux release. If you do try to use
a different version of Berkeley DB you will most likely get the error
described in the "Incompatible versions of db.h and libdb" section of
this file.

To make matters worse, prior to Perl 5.6.1, the perl binary itself
*always* included the Berkeley DB library.

If you want to use a newer version of Berkeley DB with this module, the
easiest solution is to use Perl 5.6.1 (or better) and Berkeley DB 3.x
(or better).

There are two approaches you can use to get older versions of Perl to
work with specific versions of Berkeley DB. Both have their advantages
and disadvantages.

The first approach will only work when you want to build a version of
Perl older than 5.6.1 along with Berkeley DB 3.x. If you want to use
Berkeley DB 2.x, you must use the next approach. This approach involves
rebuilding your existing version of Perl after applying an unofficial
patch. The "patches" directory in the this module's source distribution
contains a number of patch files. There is one patch file for every
stable version of Perl since 5.004. Apply the appropriate patch to your
Perl source tree before re-building and installing Perl from scratch.
For example, assuming you are in the top-level source directory for
Perl 5.6.0, the command below will apply the necessary patch. Remember
to replace the path shown below with one that points to this module's
patches directory.

patch -p1 -N </path/to/DB_File/patches/5.6.0

Now rebuild & install perl. You should now have a perl binary that can
be used to build this module. Follow the instructions in "BUILDING THE
MODULE", remembering to set the INCLUDE and LIB variables in config.in.

The second approach will work with both Berkeley DB 2.x and 3.x.
Start by building Berkeley DB as a shared library. This is from
the Berkeley DB build instructions:

Building Shared Libraries for the GNU GCC compiler

If you're using gcc and there's no better shared library example for
    your architecture, the following shared library build procedure will
    probably work.

Add the -fpic option to the CFLAGS value in the Makefile.

Rebuild all of your .o files. This will create a Berkeley DB library
    that contains .o files with PIC code. To build the shared library,
    then take the following steps in the library build directory:

% mkdir tmp
    % cd tmp
    % ar xv ../libdb.a
    % gcc -shared -o libdb.so *.o
    % mv libdb.so ..
    % cd ..
    % rm -rf tmp

Note, you may have to change the gcc line depending on the
    requirements of your system.

The file libdb.so is your shared library

Once you have built libdb.so, you will need to store it somewhere safe.

cp libdb.so /usr/local/BerkeleyDB/lib

If you now set the LD_PRELOAD environment variable to point to this
shared library, Perl will use it instead of the version of Berkeley DB
that shipped with your Linux distribution.

export LD_PRELOAD=/usr/local/BerkeleyDB/lib/libdb.so

Finally follow the instructions in "BUILDING THE MODULE" to build,
test and install this module. Don't forget to set the INCLUDE and LIB
variables in config.in.

Remember, you will need to have the LD_PRELOAD variable set anytime you
want to use Perl with Berkeley DB. Also note that if you have LD_PRELOAD
permanently set it will affect ALL commands you execute. This may be a
problem if you run any commands that access a database created by the
version of Berkeley DB that shipped with your Linux distribution.

Solaris Notes
-------------

If you are running Solaris 2.5, and you get this error when you run the
DB_File test harness:

libc internal error: _rmutex_unlock: rmutex not held.

you probably need to install a Sun patch. It has been reported that
Sun patch 103187-25 (or later revisions) fixes this problem.

To find out if you have the patch installed, the command "showrev -p"
will display the patches that are currently installed on your system.

HP-UX 10 Notes
--------------

Some people running HP-UX 10 have reported getting an error like this
when building DB_File with the native HP-UX compiler.

ld: (Warning) At least one PA 2.0 object file (DB_File.o) was detected.
    The linked output may not run on a PA 1.x system.
    ld: Invalid loader fixup for symbol "$000000A5".

If this is the case for you, Berkeley DB needs to be recompiled with
the +z or +Z option and the resulting library placed in a .sl file. The
following steps should do the trick:

1: Configure the Berkeley DB distribution with the +z or +Z C compiler
     flag:

env "CFLAGS=+z" ../dist/configure ...

2: Edit the Berkeley DB Makefile and change:

"libdb= libdb.a" to "libdb= libdb.sl".

3: Build and install the Berkeley DB distribution as usual.

HP-UX 11 Notes
--------------

Some people running the combination of HP-UX 11 and Berkeley DB 2.7.7 have
reported getting this error when the run the test harness for DB_File

...
    lib/db-btree.........Can't call method "DELETE" on an undefined value at lib/db-btree.t line 216.
    FAILED at test 26
    lib/db-hash..........Can't call method "DELETE" on an undefined value at lib/db-hash.t line 183.
    FAILED at test 22
    ...

The fix for this is to rebuild and install Berkeley DB with the bigfile
option disabled.

AIX NOTES
---------

I've had reports of a build failure like this on AIX 5.2 using the
xlC compiler.

rm -f blib/arch/auto/DB_File/DB_File.so
        LD_RUN_PATH="" ld  -bhalt:4 -bM:SRE -bI:/usr/local/5.8.1/lib/perl5/5.8.1/aix/CORE/perl.exp -bE:DB_File.exp -bnoentry -lc
    -L/usr/local/lib version.o DB_File.o  -o blib/arch/auto/DB_File/DB_File.so
    -L/usr/local/BerkeleyDB/lib -ldb -lpthread
    ld: 0711-317 ERROR: Undefined symbol: .mutex_lock
    ld: 0711-317 ERROR: Undefined symbol: .cond_signal
    ld: 0711-317 ERROR: Undefined symbol: .mutex_unlock
    ld: 0711-317 ERROR: Undefined symbol: .mutex_trylock
    ld: 0711-317 ERROR: Undefined symbol: .cond_wait
    ld: 0711-317 ERROR: Undefined symbol: .mutex_init
    ld: 0711-317 ERROR: Undefined symbol: .cond_init
    ld: 0711-317 ERROR: Undefined symbol: .mutex_destroy
    ld: 0711-345 Use the -bloadmap or -bnoquiet option to obtain more information.
    make: 1254-004 The error code from the last command is 8.

Editing Makefile.PL, and changing the line

$LIBS .= " -lpthread" if $^O eq 'aix' ;

to this

$LIBS .= " -lthread" if $^O eq 'aix' ;

fixed the problem.

FEEDBACK
========

General feedback/questions/bug reports can be sent to me at pmqs@cpan.org.

Alternatively, if you have Usenet access, you can try the
comp.databases.berkeley-db or comp.lang.perl.modules groups.

How to report a problem with DB_File.
-------------------------------------

When reporting any problem, I need the information requested below.

1. The *complete* output from running this

perl -V

Do not edit the output in any way. 
    Note, I want you to run "perl -V" and NOT "perl -v".

If your perl does not understand the "-V" option it is too
    old. DB_File needs Perl version 5.00405 or better.

2. The version of DB_File you have.
    If you have successfully installed DB_File, this one-liner will
    tell you:

perl -e 'use DB_File; print qq{DB_File ver $DB_File::VERSION\n}'

If you are running windows use this
    
       perl -e "use DB_File; print qq{DB_File ver $DB_File::VERSION\n}"

If you haven't installed DB_File then search DB_File.pm for a line
    like this:

$VERSION = "1.20" ;

3. The version of Berkeley DB used to build DB_File and the version
    that is used at runtime. (These are usually the same)

If you are using a version older than 1.85, think about upgrading. One
    point to note if you are considering upgrading Berkeley DB - the
    file formats for 1.85, 1.86, 2.0, 3.0 & 3.1 are all different.

If you have successfully installed DB_File, these commands will display
    the versions I need

perl -MDB_File -e 'print qq{Built with Berkeley DB ver $DB_File::db_ver\n}'
       perl -MDB_File -e 'print qq{Running with Berkeley DB ver $DB_File::db_version\n}'

If you are running windows use this

perl -e "use DB_File; print qq{Built with Berkeley DB ver $DB_File::db_ver\n}"
       perl -e "use DB_File; print qq{Running Berkeley DB ver $DB_File::db_version\n}"
    
 4. A copy the file config.in from the DB_File main source directory.

5. A listing of directories where Berkeley DB is installed.
    For example, if Berkeley DB is installed in /usr/BerkeleDB/lib and
    /usr/BerkeleyDB/include, I need the output from running this

ls -l /usr/BerkeleyDB/lib
        ls -l /usr/BerkeleyDB/include

6. If you are having problems building DB_File, send me a complete log
    of what happened. Start by unpacking the DB_File module into a fresh
    directory and keep a log of all the steps

[edit config.in, if necessary]
        perl Makefile.PL
        make 
        make test TEST_VERBOSE=1

7. Now the difficult one. If you think you have found a bug in DB_File
    and you want me to fix it, you will *greatly* enhance the chances
    of me being able to track it down by sending me a small
    self-contained Perl script that illustrates the problem you are
    encountering. Include a summary of what you think the problem is
    and a log of what happens when you run the script, in case I can't
    reproduce your problem on my system. If possible, don't have the
    script dependent on an existing 20Meg database. If the script you
    send me can create the database itself then that is preferred.

I realise that in some cases this is easier said than done, so if
    you can only reproduce the problem in your existing script, then
    you can post me that if you want. Just don't expect me to find your
    problem in a hurry, or at all. :-)

CHANGES
-------

See the Changes file.

Paul Marquess <pmqs@cpan.org>

${this.title}

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