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Crystal binding for the MonetDB MAPI client interface

Tested on

Crystal 0.22

Work around added for Crystal 0.23 on CentOS see crystal-lang/crystal#4719

You will need the MonetDB client package installed for this to work and also an instance of MServer5 running

We can now perform a query that emits JSON useful for SELECT statements

For more details look at


Add this to your shard.yml and run shards install or crystal dep

    github: puppetpies/crystal-monetdb-libmapi
    version: ">= 0.1.1"

Examples schemas provided under examples/

# Example code from shard crystal-monetdb-examples

require "crystal-monetdb-libmapi"
require "crystal-monetdb-libmapi/monetdb_data"
require "colorize"

class ConnectionError < Exception; end
class QueryError < Exception; end
class InternalError < Exception; end
class TimeoutError < Exception; end

host = ""
port = 50000
username = "monetdb"
password = "monetdb"
db = "threatmonitor"

mero = = host
mero.port = port
mero.username = username
mero.password = password
mero.db = db
myschema = "\"threatmonitor\""

query = "SELECT * FROM #{myschema}.fruits;"

# Alternative connect overload method to allow easy connect
# conn =
# conn.connect("localhost", "username", "password", "testschema")

result_json = mero.query_json(query)
result = mero.json_to_hash(result_json)
puts "Hash Created:".colorize(:red)
p result
puts "Display specific fields".colorize(:red)
result.each {|k,v|
  puts "Hash Key: #{k} Name: #{v["name"]} Price: #{v["price"]}"

NOTE: I recently added a workaround for compiling under Centos 7 / RHEL

We also provide an easyconnect script which allows you to provide all the host, login parameters as seen above.

There are a few benchmark tools ( Feel free to add more )

  insperf - Insert performance included my stopwatch
  randomize - Random columns / table width and data

I do hope with this project people get involved feel free to fork the project as always, raise issues where needed i just want everyone to have a good time !

Have fun!

Brian Hood