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Ruby adapter for Vertica databases

README.md

Vertica Build Status

Vertica is a pure Ruby library for connecting to Vertica databases. You can learn more about Vertica at http://www.vertica.com.

  • Connecting, including over SSL.
  • Executing queries, with results as streaming rows or buffered resultsets.
  • COPY table FROM STDIN statement to load data from your application.
  • Confirmed to work with Ruby 1.9, 2.0, and 2.1 and with Vertica version 6.x, and 7.x.
  • The library is thread-safe as of version 0.11. However, you can only run one statement at the time per connection, because the protocol is stateful.

Installation

$ gem install vertica

Or add it to your Gemfile:

gem 'vertica'
# gem 'vertica', git: 'git://github.com/wvanbergen/vertica.git' # HEAD version

Compatiblity

  • Ruby 1.8 is no longer supported, but version 0.9.x should still support it.
  • Vertica versions 4.x, and 5.x worked with at some point with this gem, but compatibility is no longer tested. It probably still works as the protocol hasn't changed as far as I am aware.

Usage

Connecting

The Vertica.connect methods takes a connection parameter hash and returns a connection object. For most options, the gem will use a default value if no value is provided.

connection = Vertica.connect({
  :host     => 'db_server',
  :user     => 'user',
  :password => 'password',
  # :ssl         => false, # use SSL for the connection
  # :port        => 5433,  # default Vertica port: 5433
  # :database    => 'db',  # there is only one database
  # :role        => nil,   # the (additional) role(s) to enable for the user.
  # :search_path => nil,   # default: <user>,public,v_catalog
  # :row_style   => :hash  # can also be :array (see below)
})

To close the connection when you're done with it, run connection.close.

Querying with unbuffered result as streaming rows

You can run simple queries using the query method, either in buffered and unbuffered mode. For large result sets, you probably do not want to use buffered results.

Get all the result rows without buffering by providing a block:

connection.query("SELECT id, name FROM my_table") do |row|
  puts row # => {:id => 123, :name => "Jim Bob"}
end

Note: you can only use the connection for one query at the time. If you try to run another query when the connection is still busy delivering the results of a previous query, a Vertica::Error::SynchronizeError will be raised. Use buffered resultsets to prevent this problem.

Store the result of the query method as a variable to get a buffered resultset:

result = connection.query("SELECT id, name FROM my_table")
connection.close

result.rows # => [{:id => 123, :name => "Jim Bob"}, {:id => 456, :name => "Joe Jack"}]
result.row_count # => 2

result.each do |row|
  puts row # => {:id => 123, :name => "Jim Bob"}
end

Row format

By default, rows are returned as hashes, using symbols for the column names. Rows can also be returned as arrays by providing a row_style:

connection.query("SELECT id, name FROM my_table", :row_style => :array) do |row|
  puts row # => [123, "Jim Bob"]
end

By adding :row_style => :array to the connection hash, all results will be returned as array.

Loading data using COPY

Using the COPY statement, you can load arbitrary data from your ruby script.

connection.copy("COPY table FROM STDIN ...") do |stdin|
  File.open('data.tsv', 'r') do |f|
    begin 
      stdin << f.gets
    end until f.eof?
  end
end

You can also provide a filename or an IO object:

connection.copy("COPY table FROM STDIN ...", "data.csv")
connection.copy("COPY table FROM STDIN ...", io)

About

This package is MIT licensed. See the LICENSE file for more information.

Development

This project comes with a test suite. The unit tests in /test/unit do not need a database connection to run, the functional tests in /test/functional do need a working database connection. You can specify the connection parameters by copying the file /test/connection.yml.example to /test/connection.yml and filling out the necessary fields.

Note that the test suite requires write access to the default schema of the provided connection, although it tries to be as little invasive as possible: all tables it creates (and drops) are prefixed with test_ruby_vertica_.

The test suite is also run by Travis CI againast Vertica 7.0.1, and Ruby 1.9.3, 2.0.0, and 2.1.1.

Authors

See also

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