mysql-rb

Native MySQL client in Ruby.

Why

• No dependencies like libmysqlclient or mariadb-connector required
• Written in Ruby and easy to contribute to
• Works on any Ruby interpreter (yes, JRuby and no JDBC/ActiveRecord issues)
• Ready for async support

API

The API tries to be backward compatible with mysql2 as much as possible.

client = MysqlRb::Client.new(host: 'localhost', username: 'root')
result = client.query("select now()")
result.to_a.size
# => 1
result.each do |row|
  row
  # => { "now()" => "2020..." }
end

result.each(as: :array) do |row|
  row
  # => ["2020..."]
end

TODO

• Connect and handshake
• Execute queries
• Parse resultsets
• query escape
• SSL support
• Type casting
• Support for CLIENT_SESSION_TRACK
• Custom error classes based on error number
• Handling reconnections

Design choices

This library does not attempt to capture complete support of MySQL protocol, but it aims to do enough to cover what modern applications and modern MySQL server (5.7+) needs.

Here are some of the choices that were deliberately made:

• UTF8MB4_GENERAL_CI is the only allowed charset
• CLIENT_DEPRECATE_EOF flag is always set

Contributions to support a wider protocol are welcome.

Performance and benchmarking

It's expected for this Ruby driver to be less performant than mysql2 which is a C extension that wraps libmysqlclient.

However, with most MySQL queries and network roundtrips taking multiple milliseconds, it's arguable if some extra overhead from the client is tolerable.

To the limited knowledge of the author, it's not completely fair to compare GC.stat of a Ruby client to GC.stat of a C ext because allocations made in C land would not be counted.

For that reason, the author chose to compare process RSS (Resident set size) rather than Ruby's internal state of memory.

Check example/bench_mem.rb for code of the benchmark.

iteration	queries	RSS (kb), mysql-rb	RSS (kb), mysql2
1	1500	25688	28136
2	3000	26368	29520
3	4500	26528	30200
4	6000	27028	30200
5	7500	27188	30200
6	9000	27432	30204
7	10500	27500	30204
8	12000	27524	25920
9	13500	27524	22684
10	15000	27580	22788

The difference in RSS is not orders of magnitude away between a Ruby client and the C client.

The decrease in RSS in mysql2 after the 7th iteration can be explain by Ruby's GC kicking in (remember that C ext doesn't cause to many allocations and it would take longer for GC to start collecting objects).