NAME
    DBIx::Table::TestDataGenerator - Automatic test data creation, cross
    DBMS

VERSION
    Version 0.0.4

SYNOPSIS
            use DBIx::Table::TestDataGenerator;
        
            my $generator = DBIx::Table::TestDataGenerator->new(
                    dsn                    => $data_source_name,
                    user                   => $db_user_name,
                    password               => $db_password,          
                    table                  => $target_table_name,
            );

            #simple usage:
            $generator->create_testdata(
                    target_size            => $target_size,
                    num_random             => $num_random,            
            );

            #extended usage handling a self-reference of the target table:
            $generator->create_testdata(
                            target_size        => $target_size,
                            num_random         => $num_random,                
                            max_tree_depth     => $max_tree_depth,
                            min_children       => $min_children,
                            min_roots          => $min_roots,
            );

DESCRIPTION
    There is often the need to create test data in database tables, e.g. to
    test database client performance. The existence of constraints on a
    table makes it non-trivial to come up with a way to add records to it.

    The current module inspects the tables' constraints and adds a desired
    number of records. The values of the fields either come from the table
    itself (possibly incremented to satisfy uniqueness constraints) or from
    tables referenced by foreign key constraints. The choice of the copied
    values is random for a number of runs the user can choose, afterwards
    the values are chosen randomly from a cache, reducing database traffic
    for performance reasons. One nice thing about this way to construct new
    records is that the additional data is similar to the data initially
    present in the table.

    A main goal of the module is to reduce configuration to the absolute
    minimum by automatically determining information about the target table,
    in particular its constraints. Another goal is to support as many DBMSs
    as possible, this has been achieved by basing it on DBIx::Class modules.

    In the synopsis, an extended usage has been mentioned. This refers to
    the common case of having a self-reference on a table, i.e. a one-column
    wide foreign key of a table to itself where the referenced column
    constitutes the primary key. Such a parent-child relationship defines a
    rootless tree and when generating test data it may be useful to have
    some control over the growth of this tree. One such case is when the
    parent-child relation represents a navigation tree and a client
    application processes this structure. In this case, one would like to
    have a meaningful, balanced tree structure since this corresponds to
    real-world examples. To control tree creation the parameters
    max_tree_depth, min_children and min_roots are provided. Note that the
    nodes are being added in a depth-first manner.

SUBROUTINES/METHODS
  new
    Arguments:

    *   dsn: required DBI data source name

    *   user: required database user

    *   password: required database user's password

    *   table: required name of the target table

    Return value:

    A new TestDataGenerator object

  dsn
    Accessor for the DBI data source name.

  user
    Accessor for the database user.

  password
    Accessor for the database user's password.

  table
    Accessor for the name of the target table.

  create_testdata
    This is the main method, it creates and adds new records to the target
    table. In case one of the arguments max_tree_depth, min_children or
    min_roots has been provided, the other two must be provided as well.

    Arguments:

    *   target_size

        The target number of rows to be reached.

    *   num_random

        The first $num_random number of records use fresh random choices for
        their values taken from tables referenced by foreign key relations
        or the target table itself. These values are stored in a cache and
        re-used for the remaining (target_size - $num_random) records. Note
        that even for the remaining records there is some randomness since
        the combination of cached values coming from columns involved in
        different constraints is random.

    *   max_tree_depth

        In case of a self-reference, the maximum depth at which new records
        will be inserted. The minimum value for this parameter is 2.

    *   min_children

        In case of a self-reference, the minimum number of children each
        handled parent node will get. A possible exception is the last
        handled parent node if the execution stops before $min_children
        child nodes have been added to it.

    *   min_roots

        In case of a self-reference, the minimum number of root elements
        existing after completion of the call to create_testdata. A record
        is considered to be a root element if the corresponding parent id is
        null or equal to the child id.

    Returns:

    Nothing, only called for the side-effect of adding new records to the
    target table. (This may change, see the section FURTHER DEVELOPMENT.)

INSTALLATION AND CONFIGURATION
    To install this module, run the following commands:

            perl Build.PL
            ./Build
            ./Build test
            ./Build install

LIMITATIONS
    *   Currently, the module executes the inserts in one big transaction if
        the database handle has not set AutoCommit to true, but this will
        change, see the section FURTHER DEVELOPMENT.

    *   Only uniqueness and foreign key constraints are taken into account.
        Constraints such as check constraints, which are very diverse and
        database specific, are not handled (and most probably will not be).

    *   Uniqueness constraints involving only columns which the TableProbe
        class does not know how to increment cannot be handled. Typically,
        all string and numeric data types are supported and the set of
        supported data types is defined by the list provided by the
        TableProbe method get_type_preference_for_incrementing(). I am
        thinking about allowing date incrementation, too, it would be
        necessary then to at least add a configuration parameter defining
        what time incrementation step to use.

    *   When calling create_testdata, max_tree_depth = 1 should be allowed,
        too, meaning that all new records will be root records.

    *   Added records that are root node with respect to the self-reference
        always have the parent id equal to their pkey. It may be that in the
        case in question the convention is such that root nodes are
        identified by having the parent id set to NULL.

FURTHER DEVELOPMENT
    *   The current version handles uniqueness constraints by picking out a
        column involved in the constraint and incrementing it appropriately.
        This should be made customizable in future versions.

    *   Support for transactions and specifying transaction sizes will be
        added.

    *   It will be possible to get the SQL source of all generated inserts
        without having them executed on the database.

    *   Currently one cannot specify a seed for the random selections used
        to define the generated records since the used class
        DBIx::Class::Helper::ResultSet::Random does not provide this. For
        reproducible tests this would be a nice feature.

ACKNOWLEDGEMENTS
    *   Version 0.001:

        A big thank you to all perl coders on the dbi-dev, DBIx-Class and
        perl-modules mailing lists and on PerlMonks who have patiently
        answered my questions and offered solutions, advice and
        encouragement, the Perl community is really outstanding.

        Special thanks go to Tim Bunce (module name / advice on keeping the
        module extensible), Jonathan Leffler (module naming discussion /
        relation to existing modules / multiple suggestions for features),
        brian d foy (module naming discussion / mailing lists /
        encouragement) and the following Perl monks (see the threads for
        user jds17 for details): chromatic, erix, technojosh, kejohm,
        Khen1950fx, salva, tobyink (3 of 4 discussion threads!), Your
        Mother.

    *   Version 0.002:

        Martin J. Evans was the first developer giving me feedback and nice
        bug reports on Version 0.001, thanks a lot!

AUTHOR
    Jose Diaz Seng, "<josediazseng at gmx.de>"

BUGS
    Please report any bugs or feature requests to
    "bug-dbix-table-testdatagenerator at rt.cpan.org", or through the web
    interface at
    <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=DBIx-Table-TestDataGener
    ator>. I will be notified, and then you'll automatically be notified of
    progress on your bug as I make changes.

SUPPORT
    You can find documentation for this module with the perldoc command.

        perldoc DBIx::Table::TestDataGenerator

    You can also look for information at:

    *   RT: CPAN's request tracker (report bugs here)

        <http://rt.cpan.org/NoAuth/Bugs.html?Dist=DBIx-Table-TestDataGenerat
        or>

    *   AnnoCPAN: Annotated CPAN documentation

        <http://annocpan.org/dist/DBIx-Table-TestDataGenerator>

    *   CPAN Ratings

        <http://cpanratings.perl.org/d/DBIx-Table-TestDataGenerator>

    *   Search CPAN

        <http://search.cpan.org/dist/DBIx-Table-TestDataGenerator/>

LICENSE AND COPYRIGHT
    Copyright 2012 Jose Diaz Seng.

    This program is free software; you can redistribute it and/or modify it
    under the terms of either: the GNU General Public License as published
    by the Free Software Foundation; or the Artistic License.

    See http://dev.perl.org/licenses/ for more information.