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cassandra-fdw

PostgreSQL Foreign Data Wrapper for Cassandra

Requirements

  • PostgreSQL 9.3+
  • PostgreSQL development packages (postgresql-server-dev-9.x)
  • Cassandra 2.1+, 2.2+, 3+

Features

  • Foreign schema import
  • Full CQL types support
  • CQL query optimizations

How to install

install additional packages

sudo apt-get install git build-essential python-dev python-setuptools pgxnclient

install Multicorn

sudo pgxn install multicorn

install Cassandra driver and modules

sudo easy_install pip
sudo pip install cassandra-driver
sudo pip install pytz

clone repository

git clone https://github.com/rankactive/cassandra-fdw.git

install FDW

cd cassandra-fdw
python setup.py install

Usage

-- Create test database
CREATE DATABASE fdw_test;

Switch to database fdw_test

-- Create extension for database
CREATE EXTENSION multicorn;
-- Create server
CREATE SERVER fdw_server FOREIGN DATA WRAPPER multicorn
OPTIONS (
  wrapper 'cassandra-fdw.CassandraFDW',
  hosts '10.10.10.1,10.10.10.2',
  port '9042',
  username 'cassandra user', -- optional
  password 'cassandra password' -- optional
);
-- Create foreign table
CREATE FOREIGN TABLE fdw_table
(
  col1 text,
  col2 int,
  col3 bigint
) SERVER fdw_server OPTIONS (keyspace 'cassandra keyspace', columnfamily 'cassandra columnfamily');

Use it!

SELECT * FROM fdw_table WHERE col1 = 'some text';
INSERT INTO fdw_table VALUES ('text', 123, 1234);

By default, the concurrency level of modifications is 4. It means that batch modifications will be sent in 4 threads to Cassandra. To change it use:

ALTER SERVER fdw_srv OPTIONS (modify_concurency 'your integer value');

Or if it has been set before, use:

ALTER SERVER fdw_srv OPTIONS (SET modify_concurency 'your integer value');

If you want to use updates and deletes, you must create column named "__rowid__" with type "TEXT"

Import foreign schema example:

CREATE SCHEMA fdw_test;
IMPORT FOREIGN SCHEMA cassandra_keyspace FROM SERVER fdw_server INTO fdw_test;

Types mapping

CQL type PostgreSQL type
bigint bigint
blob bytea
boolean boolean
counter bigint
date date
decimal decimal
double float8
float float4
inet inet
int int
list<type> type[]
map<type, type> json
set<type> type[]
smallint smallint
text text
time timetz
timestamp timestamptz
timeuuid uuid
tinyint smallint
tuple<type,type,...> json
uuid uuid
varint int