Thomas Klausner > DBIx-SchemaChecksum > DBIx::SchemaChecksum

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Module Version: 1.005   Source  

NAME ^

DBIx::SchemaChecksum - Generate and compare checksums of database schematas

VERSION ^

version 1.005

SYNOPSIS ^

    my $sc = DBIx::SchemaChecksum->new( dbh => $dbh );
    print $sc->checksum;

    # Or use the included script, scs.pl

DESCRIPTION ^

When you're dealing with several instances of the same database (eg. developer, testing, stage, production), it is crucial to make sure that all databases use the same schema. This can be quite an hair-pulling experience, and this module should help you keep your hair (if you're already bald, it won't make your hair grow back, sorry...)

DBIx::SchemaChecksum gets schema information (tables, columns, primary keys, foreign keys and some more depending on your DBD) and generates a SHA1 digest. This digest can then be used to easily verify schema consistency across different databases.

Caveat: The same schema might produce different checksums on different database versions.

DBIx::SchemaChecksum is tested with PostgreSQL 8.3 to 9.1 and SQLite (but see below). I assume that thanks to the abstraction provided by the DBI it works with most databases. If you try DBIx::SchemaChecksum with different database systems, I'd love to hear some feedback...

Scripts

Please take a look at the "scs.pl" in bin script included in this distribution.

Talks

You can find more information on the rational, usage & implementation in the slides for my talk at the Austrian Perl Workshop 2012, available here: http://domm.plix.at/talks/dbix_schemachecksum.html

METHODS ^

checksum

    my $sha1_hex = $self->checksum();

Gets the schemadump and runs it through Digest::SHA1, returning the current checksum.

schemadump

    my $schemadump = $self->schemadump;

Returns a string representation of the whole schema (as a Data::Dumper Dump).

Lazy Moose attribute.

_build_schemadump

Internal method to build schemadump. Keep out!

_build_schemadump_schema

    my $hashref = $self->_build_schemadump_schema( $schema );

This is the main entry point for checksum calculations per schema. Method-modifiy it if you need to alter the complete schema data structure before/after checksumming.

Returns a HashRef like:

    {
        tables => $hash_ref
    }

_build_schemadump_tables

    my $hashref = $self->_build_schemadump_tables( $schema );

Iterate through all tables in a schema, calling _build_schemadump_table for each table and collecting the results in a HashRef

_build_schemadump_table

    my $hashref = $self->_build_schemadump_table( $schema, $table );

Get metadata on a table (columns, primary keys & foreign keys) via DBI introspection.

This is a good place to method-modify if you need some special processing for your database

Returns a hashref like

    {
        columns      => $data,
        primary_keys => $data,
        foreign_keys => $data,
    }

_build_schemadump_column

    my $hashref = $self->_build_schemadump_column( $schema, $table, $column, $raw_dbi_data );

Does some cleanup on the data returned by DBI.

update_path

    my $update_info = $self->update_path

Lazy Moose attribute that returns the datastructure needed by apply_sql_update.

_build_update_path

_build_update_path reads in all files ending in ".sql" in $self->sqlsnippetdir. It builds something like a linked list of files, which are chained by their preSHA1sum and postSHA1sum.

get_checksums_from_snippet

    my ($pre, $post) = $self->get_checksums_from_snippet( $filename );

Returns a list of the preSHA1sum and postSHA1sum for the given file in sqlnippetdir.

The file has to contain this info in SQL comments, eg:

  -- preSHA1sum: 89049e457886a86886a4fdf1f905b69250a8236c
  -- postSHA1sum: d9a02517255045167053ea92dace728e1389f8ca

  alter table foo add column bar;

dbh

Database handle (DBH::db). Moose attribute

catalog

The database catalog searched for data. Not implemented by all DBs. See DBI::table_info

Default %.

Moose attribute

schemata

An Arrayref containg names of schematas to include in checksum calculation. See DBI::table_info

Default %.

Moose attribute

sqlsnippetdir

Path to the directory where the sql change files are stored.

Moose attribute

verbose

Be verbose or not. Default: 0

driveropts

Additional options for the specific database driver.

NAME ^

DBIx::SchemaChecksum - Generate and compare checksums of database schematas

SEE ALSO ^

bin/scs.pl for a commandline frontend powered by MooseX::App

ACKNOWLEDGEMENTS ^

Thanks to Klaus Ita and Armin Schreger for writing the core code. I just glued it together...

This module was written for revdev http://www.revdev.at, a nice litte software company run by Koki, Domm (http://search.cpan.org/~domm/) and Maros (http://search.cpan.org/~maros/).

AUTHORS ^

COPYRIGHT AND LICENSE ^

This software is copyright (c) 2012 by Thomas Klausner, Maroš Kollár, Klaus Ita.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

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