Add this line to your application's Gemfile:

gem 'mini_sql'

And then execute:

$ bundle

Or install it yourself as:

$ gem install mini_sql


MiniSql is a very simple, safe and fast SQL executor and mapper for PG and Sqlite.

pg_conn = PG.connect(db_name: 'my_db')
conn = MiniSql::Connection.get(pg_conn)

puts conn.exec('update table set column = 1 where id in (1,2)')
# returns 2 if 2 rows changed

conn.query("select 1 id, 'bob' name").each do |user|
  puts # bob
  puts # 1

p conn.query_single('select 1 union select 2')
# [1,2]

p conn.query_hash('select 1 as a, 2 as b union select 3, 4')
# [{"a" => 1, "b"=> 1},{"a" => 3, "b" => 4}

The query builder

You can use the simple query builder interface to compose queries.

builder ="select * from topics /*where*/ /*limit*/")

builder.where('created_at > ?', - 400)

if look_for_something
  builder.where("title = :title", title: 'something')


builder.query.each do |t|
  puts t.title

The builder allows for order_by, where, select, set, limit, join, left_join and offset.

Is it fast?

Yes, it is very fast. See benchmarks in the bench directory.

As a rule it will outperform similar naive PG code while remaining safe.

pg_conn = PG.connect(db_name: 'my_db')

# this is slower, and less safe
result = pg_conn.async_exec('select * from table')
result.each do |r|
  name = r['name']
# ideally you want to remember to run r.clear here

# this is faster and safer
conn = MiniSql::Connection.get(pg_conn)
r = conn.query('select * from table')

r.each do |row|
  name =


In PG gem version 1.0 and below you should be careful to clear results. If you do not you risk memory bloat. See: Sam's blog post.

MiniSql is careful to always clear results as soon as possible.

Timestamp decoding

MiniSql's default type mapper prefers treating timestamp without time zone columns as utc. This is done to ensure widest amount of compatability and is a departure from the default in the PG 1.0 gem. If you wish to amend behavior feel free to pass in a custom type_map.

I want more features!

MiniSql is designed to be very minimal. Even though the query builder and type materializer give you a lot of mileage, it is not intended to be a fully fledged ORM. If you are looking for an ORM I recommend investigating ActiveRecord or Sequel which provide significantly more features.


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


Bug reports and pull requests are welcome on GitHub at 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.


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

Code of Conduct

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