A Pure Ruby CDB reader/writer w/64 bit extensions
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README.md

PureCDB

A Pure Ruby CDB reader/writer w/64 bit extensions

For information about CDB, see: http://cr.yp.to/cdb.html

The motivation for writing this was:

  • Bernstein's CDB format can only handle files up to 4GB. For a past project we needed a simple CDB style file for datasets several times that.

  • The C library is under a license that prevents us from releasing modified versions of it, but the format is so simple that writing our own reader and writer was easy.

  • We don't like depending on C extensions for Ruby code if we don't have to.

Installation

Add this line to your application's Gemfile:

gem 'purecdb'

And then execute:

$ bundle

Or install it yourself as:

$ gem install purecdb

Basic Usage

To create a 32 bit (standard) CDB file:

    PureCDB::Writer.open("/tmp/somecdbfile.cdb") do |cdb| 
     cdb.store("key","value")
    end

To instead create a 64 bit file, pass {mode: 64} as the second argument to PureCDB::Writer#open .

To read a CDB file (auto-detecting standard 32-bit or extended 64-bit) CDB files:

    PureCDB::Reader.open("/tmp/somecdbfile.cdb") do |r|
       p r.values("key")
    end

To require a 32 or 64 bit file specifically, pass {mode: 32} or {mode: 64} as the second argument to PureCDB::Reader#open.

See PureCDB::Reader#new for additional usage.

64-bit Format

The 64 bit file format follows http://cr.yp.to/cdb/cdb.txt except that any reference to 32-bit should be replaced by 64-bit, and that a 64 bit file ends with the magic cookie "cdb64:01"

Development

After checking out the repo, run bin/setup to install dependencies. Then, 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 to create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

To run the Rspec tests, you need tinycdb or a command-line compatible implementation installed for interoperability tests.

Contributing

  1. Fork it ( https://github.com/hokstadconsulting/purecdb/fork )
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request