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mysql数据库源代码

                                     DB_File

                                  Version 1.805

                                  1st Sep 2002

 	Copyright (c) 1995-2002 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, 3 or 4 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, 3.x or 4.x, 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.sleepycat.com.
      The latest version of Berkeley DB is always available there. It
      is recommended that you use the most recent version available at
      the Sleepycat site.

      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


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 both version 1 and version
2 of Berkeley DB installed on your system and DB_File attempts to
build using the db.h for Berkeley DB version 2 and the version 1
library. Unfortunately the two versions aren't compatible with each
other. The undefined symbol error is actually 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.

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.


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

BerkeleyDB 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 needs compatible versions of libdb & db.h
          you have db.h version 2.3.7 and 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.

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 BerkeleyDB to use.
          If you are running Linux, please read the Linux Notes section
          below.


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

Newer 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