1DBI::PurePerl(3)      User Contributed Perl Documentation     DBI::PurePerl(3)
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NAME

6       DBI::PurePerl -- a DBI emulation using pure perl (no C/XS compilation
7       required)
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SYNOPSIS

10        BEGIN { $ENV{DBI_PUREPERL} = 2 }
11        use DBI;
12

DESCRIPTION

14       This is a pure perl emulation of the DBI internals.  In almost all
15       cases you will be better off using standard DBI since the portions of
16       the standard version written in C make it *much* faster.
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18       However, if you are in a situation where it isn't possible to install a
19       compiled version of standard DBI, and you're using pure-perl DBD driv‐
20       ers, then this module allows you to use most common features of DBI
21       without needing any changes in your scripts.
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EXPERIMENTAL STATUS

24       DBI::PurePerl is new so please treat it as experimental pending more
25       extensive testing.  So far it has passed all tests with DBD::CSV,
26       DBD::AnyData, DBD::XBase, DBD::Sprite, DBD::mysqlPP.  Please send bug
27       reports to Jeff Zucker at <jeff@vpservices.com> with a cc to
28       <dbi-dev@perl.org>.
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USAGE

31       The usage is the same as for standard DBI with the exception that you
32       need to set the enviornment variable DBI_PUREPERL if you want to use
33       the PurePerl version.
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35        DBI_PUREPERL == 0 (the default) Always use compiled DBI, die
36                          if it isn't properly compiled & installed
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38        DBI_PUREPERL == 1 Use compiled DBI if it is properly compiled
39                          & installed, otherwise use PurePerl
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41        DBI_PUREPERL == 2 Always use PurePerl
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43       You may set the enviornment variable in your shell (e.g. with set or
44       setenv or export, etc) or else set it in your script like this:
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46        BEGIN { $ENV{DBI_PUREPERL}=2 }
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48       before you "use DBI;".
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INSTALLATION

51       In most situations simply install DBI (see the DBI pod for details).
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53       In the situation in which you can not install DBI itself, you may manu‐
54       ally copy DBI.pm and PurePerl.pm into the appropriate directories.
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56       For example:
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58        cp DBI.pm      /usr/jdoe/mylibs/.
59        cp PurePerl.pm /usr/jdoe/mylibs/DBI/.
60
61       Then add this to the top of scripts:
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63        BEGIN {
64          $ENV{DBI_PUREPERL} = 1;      # or =2
65          unshift @INC, '/usr/jdoe/mylibs';
66        }
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68       (Or should we perhaps patch Makefile.PL so that if DBI_PUREPERL is set
69       to 2 prior to make, the normal compile process is skipped and the files
70       are installed automatically?)
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DIFFERENCES BETWEEN DBI AND DBI::PurePerl

73       Attributes
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75       Boolean attributes still return boolean values but the actual values
76       used may be different, i.e., 0 or undef instead of an empty string.
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78       Some handle attributes are either not supported or have very limited
79       functionality:
80
81         ActiveKids
82         InactiveDestroy
83         Kids
84         Taint
85         TaintIn
86         TaintOut
87
88       (and probably others)
89
90       Tracing
91
92       Trace functionality is more limited and the code to handle tracing is
93       only embeded into DBI:PurePerl if the DBI_TRACE environment variable is
94       defined.  To enable total tracing you can set the DBI_TRACE environment
95       variable as usual.  But to enable individual handle tracing using the
96       trace() method you also need to set the DBI_TRACE environment variable,
97       but set it to 0.
98
99       Parameter Usage Checking
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101       The DBI does some basic parameter count checking on method calls.
102       DBI::PurePerl doesn't.
103
104       Speed
105
106       DBI::PurePerl is slower. Although, with some drivers in some contexts
107       this may not be very significant for you.
108
109       By way of example... the test.pl script in the DBI source distribution
110       has a simple benchmark that just does:
111
112           my $null_dbh = DBI->connect('dbi:NullP:','','');
113           my $i = 10_000;
114           $null_dbh->prepare('') while $i--;
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116       In other words just prepares a statement, creating and destroying a
117       statement handle, over and over again.  Using the real DBI this runs at
118       ~4550 handles per second whereas DBI::PurePerl manages ~2800 per second
119       on the same machine (not too bad really).
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121       May not fully support hash()
122
123       If you want to use type 1 hash, i.e., "hash($string,1)" with
124       DBI::PurePerl, you'll need version 1.56 or higher of Math::BigInt
125       (available on CPAN).
126
127       Doesn't support preparse()
128
129       The DBI->preparse() method isn't supported in DBI::PurePerl.
130
131       Doesn't support DBD::Proxy
132
133       There's a subtle problem somewhere I've not been able to identify.
134       DBI::ProxyServer seem to work fine with DBI::PurePerl but DBD::Proxy
135       does not work 100% (which is sad because that would be far more useful
136       :) Try re-enabling t/80proxy.t for DBI::PurePerl to see if the problem
137       that remains will affect you're usage.
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139       Others
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141         can() - doesn't have any special behaviour
142
143       Please let us know if you find any other differences between DBI and
144       DBI::PurePerl.
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AUTHORS

147       Tim Bunce and Jeff Zucker.
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149       Tim provided the direction and basis for the code.  The original idea
150       for the module and most of the brute force porting from C to Perl was
151       by Jeff. Tim then reworked some core parts to boost the performance and
152       accuracy of the emulation. Thanks also to Randal Schwartz and John
153       Tobey for patches.
154

156       Copyright (c) 2002  Tim Bunce  Ireland.
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158       See COPYRIGHT section in DBI.pm for usage and distribution rights.
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162perl v5.8.8                       2006-02-07                  DBI::PurePerl(3)
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