ruby-duckdb

Description

ruby-duckdb is Ruby binding for DuckDB database engine

Requirement

You must have DuckDB engine installed in order to build/use this module.

How to Install

gem install duckdb

or you must specify the location of the C header and library files:

gem install duckdb -- --with-duckdb-include=/duckdb_header_directory --with-duckdb-lib=/duckdb_library_directory

Usage

require 'duckdb'

db = DuckDB::Database.open # database in memory
con = db.connect

con.query('CREATE TABLE users (id INTEGER, name VARCHAR(30))')

con.query("INSERT into users VALUES(1, 'Alice')")
con.query("INSERT into users VALUES(2, 'Bob')")
con.query("INSERT into users VALUES(3, 'Cathy')")

result = con.query('SELECT * from users')
result.each do |row|
  p row
end

Or, you can use block.

require 'duckdb'

DuckDB::Database.open do |db|
  db.connect do |con|
    con.query('CREATE TABLE users (id INTEGER, name VARCHAR(30))')

    con.query("INSERT into users VALUES(1, 'Alice')")
    con.query("INSERT into users VALUES(2, 'Bob')")
    con.query("INSERT into users VALUES(3, 'Cathy')")

    result = con.query('SELECT * from users')
    result.each do |row|
      p row
    end
  end
end

using BLOB column

BLOB is available with DuckDB v0.2.5 or later. Use DuckDB::Blob.new or use sting#force_encoding(Encoding::BINARY)

require 'duckdb'

DuckDB::Database.open do |db|
  db.connect do |con|
    con.query('CREATE TABLE blob_table (binary_data BLOB)')
    stmt = DuckDB::PreparedStatement.new(con, 'INSERT INTO blob_table VALUES ($1)')

    stmt.bind(1, DuckDB::Blob.new("\0\1\2\3\4\5"))
    # stmt.bind(1, "\0\1\2\3\4\5".force_encoding(Encoding::BINARY))
    stmt.execute

    result = con.query('SELECT binary_data FROM blob_table')
    p result.first.first
  end
end

Appender

Appender class provides Ruby interface of DuckDB Appender

require 'duckdb'
require 'benchmark'

def insert
  DuckDB::Database.open do |db|
    db.connect do |con|
      con.query('CREATE TABLE users (id INTEGER, name VARCHAR(30))')
      10000.times do
        con.query("INSERT into users VALUES(1, 'Alice')")
      end
    end
  end
end

def prepare
  DuckDB::Database.open do |db|
    db.connect do |con|
      con.query('CREATE TABLE users (id INTEGER, name VARCHAR(30))')
      stmt = con.prepared_statement('INSERT INTO users VALUES($1, $2)')
      10000.times do
        stmt.bind(1, 1)
        stmt.bind(2, 'Alice')
        stmt.execute
      end
    end
  end
end

def append
  DuckDB::Database.open do |db|
    db.connect do |con|
      con.query('CREATE TABLE users (id INTEGER, name VARCHAR(30))')
      appender = con.appender('users')
      10000.times do
        appender.begin_row
        appender.append(1)
        appender.append('Alice')
        appender.end_row
      end
      appender.flush
    end
  end
end

Benchmark.bm(8) do |x|
  x.report('insert') { insert }
  x.report('prepare') { prepare }
  x.report('append') { append }
end

# =>
#                user     system      total        real
# insert     0.637439   0.000000   0.637439 (  0.637486 )
# prepare    0.230457   0.000000   0.230457 (  0.230460 )
# append     0.012666   0.000000   0.012666 (  0.012670 )

Configuration

Config class provides Ruby interface of DuckDB configuration.

require 'duckdb'
config = DuckDB::Config.new
config['default_order'] = 'DESC'
db = DuckDB::Database.open(nil, config)
con = db.connect
con.query('CREATE TABLE numbers (number INTEGER)')
con.query('INSERT INTO numbers VALUES (2), (1), (4), (3)')

# number is ordered by descending.
r = con.query('SELECT number FROM numbers ORDER BY number')
r.first.first # => 4