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README.rdoc

Ruby Extract-Transform-Load (ETL) tool.

Requirements

  • Ruby 1.8.5 or higher

  • Rubygems

Online Documentation

Available at activewarehouse.rubyforge.org/docs/activewarehouse-etl.html

Features

Current supported features:

  • ETL Domain Specific Language (DSL) - Control files are specified in a Ruby-based DSL

  • Multiple source types. Current supported types:

    • Fixed-width and delimited text files

    • XML files through SAX

    • Apache combined log format

  • Multiple destination types - file and database destinations

  • Support for extracting from multiple sources in a single job

  • Support for writing to multiple destinations in a single job

  • A variety of built-in transformations are included:

    • Date-to-string, string-to-date, string-to-datetime, string-to-timestamp

    • Type transformation supporting strings, integers, floats and big decimals

    • Trim

    • SHA-1

    • Decode from an external decode file

    • Default replacement for empty values

    • Ordinalize

    • Hierarchy lookup

    • Foreign key lookup

    • Ruby blocks

    • Any custom transformation class

  • A variety of build-in row-level processors

    • Check exists processor to determine if the record already exists in the destination database

    • Check unique processor to determine whether a matching record was processed during this job execution

    • Copy field

    • Rename field

    • Hierarchy exploder which takes a tree structure defined through a parent id and explodes it into a hierarchy bridge table

    • Surrogate key generator including support for looking up the last surrogate key from the target table using a custom query

    • Sequence generator including support for context-sensitive sequences where the context can be defined as a combination of fields from the source data

    • New row-level processors can easily be defined and applied

  • Pre-processing

    • Truncate processor

  • Post-processing

    • Bulk import using native RDBMS bulk loader tools

  • Virtual fields - Add a field to the destination data which doesn't exist in the source data

  • Built in job and record meta data

  • Support for type 1 and type 2 slowly changing dimensions

    • Automated effective date and end date time stamping for type 2

    • CRC checking

Dependencies

ActiveWarehouse ETL depends on the following gems:

  • ActiveSupport Gem

  • ActiveRecord Gem

  • FasterCSV Gem

  • AdapterExtensions Gem

Usage

Once the ActiveWarehouse ETL gem is installed jobs can be invoked using the included `etl` script. The etl script includes several command line options and can process multiple control files at a time.

Command line options:

  • --help, -h: Display the usage message.

  • --config, -c: Specify a database.yml configuration file to use.

  • --limit, -l: Specify a limit to the number of rows to process. This option is currently only applicable to database sources.

  • --offset, -o: Specify the start offset for reading from the source. This option is currently only applicable to database sources.

  • --newlog, -n: Instruct the engine to create a new ETL log rather than append to the last ETL log.

  • --skip-bulk-import, -s: Skip any bulk imports.

  • --read-locally: Read from the local cache (skip source extraction)

Control File Examples

Control file examples can be found in the examples directory.

Running Tests

Current state:

  • 11 failures on MySQL

  • 1 failure on Postgres

The tests require:

  • gem install shoulda

  • gem install flexmock

  • gem install pg (if you want to run the tests on pg)

The tests subfolder contains examples database.yml for mysql and postgres.

To run the tests:

  • rake test DB=postgresql (for postgres)

  • otherwise just rake test

Feedback

This is a work in progress. Comments should be made on the activewarehouse-discuss mailing list at the moment. Contributions are always welcome.

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