TableSaw

This gem creates a PSQL dump file (data only) from a Postgres database by only dumping a subset of data defined by a manifest file.

It will automatically retrieve the foreign key dependencies of your tables as long as the foreign key constraints are defined.

Installation

Add this line to your application's Gemfile:

gem 'table_saw'

And then execute:

$ bundle

Or install it yourself as:

$ gem install table_saw

Usage

table-saw dump -m manifest.yml

The command above will read your configuration from manifest.yml and create a dump file output.dump. The database connection properties can be supplied similar to the pg_dump tool provided by Postgres:

Usage:
  table-saw dump -m, --manifest=MANIFEST

Options:
  -u, [--url=URL]             # Default value is $DATABASE_URL
  -d, [--dbname=DBNAME]       # Default value is $PGDATABASE
  -h, [--host=HOST]           # Default value is $PGHOST
  -p, [--port=PORT]           # Default value is $PGPORT
  -U, [--user=USER]           # Default value is $PGUSER
      [--password=PASSWORD]   # Default value is $PGPASSWORD
  -m, --manifest=MANIFEST
  -o, [--output=OUTPUT]       # Default value is 'output.dump'

The manifest file describes which tables you want to dump from your Postgres database:

variables:
  author_id: 24
tables:
  - table: books
    query: "select * from books where author_id = %{author_id}"

This will only fetch records from the books table where author_id = 24 and will also fetch the record from the authors table where id = 24.

Assuming there is a chapters table with a foreign key reference of book_id to the books table, the above manifest file will not automatically retrieve those records. If chapters records are also desired, there a couple ways to accomplish this:

variables:
  author_id: 24
tables:
  - table: books
    query: "select * from books where author_id = %{author_id}"
    has_many:
      - chapters

or

variables:
  author_id: 24
tables:
  - table: chapters
    query: "select * from chapters inner join books on books.id = chapters.book_id where books.author_id = %{author_id}"

The output of the 2 manifest files above are exactly the same. The dump file will contain all the relevant records from the authors, books and chapters tables.

Once your dump file has been created, you can import the data using psql:

table-saw dump -m manifest.yml -o chapters.dump
psql -h localhost -U postgres -d library < chapters.dump

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/hasghari/table_saw. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the TableSaw project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.