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Jonathan Ellis
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README.asc
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README.asc
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Executive summary
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-----------------
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Cassandra is a partitioned row store. Rows are organized into tables with a required primary key.
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Cassandra is a highly scalable, eventually consistent, distributed, structured
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key-value store.
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http://wiki.apache.org/cassandra/Partitioners[Partitioning] means that Cassandra can distribute your data across multiple machines in an application-transparent matter. Cassandra will automatically repartition as machines are added and removed from the cluster.
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http://wiki.apache.org/cassandra/DataModel[Row store] means that like relational databases, Cassandra organizes data by rows and columns. The Cassandra Query Language (CQL) is a close relative of SQL.
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Project description
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-------------------
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Cassandra brings together the distributed systems technologies from Dynamo
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and the data model from Google's BigTable. Like Dynamo, Cassandra is
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eventually consistent. Like BigTable, Cassandra provides a ColumnFamily-based
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data model richer than typical key/value systems.
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For more information see http://cassandra.apache.org/
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For more information, see http://cassandra.apache.org/[the Apache Cassandra web site].
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Requirements
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------------
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* Java >= 1.7 (OpenJDK and Sun have been tested)
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. Java >= 1.7 (OpenJDK and Oracle JVMS have been tested)
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. Python 2.7 (for cqlsh)
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Getting started
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---------------
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@ -24,73 +20,74 @@ Getting started
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This short guide will walk you through getting a basic one node cluster up
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and running, and demonstrate some simple reads and writes.
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* tar -zxvf apache-cassandra-$VERSION.tar.gz
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* cd apache-cassandra-$VERSION
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* sudo mkdir -p /var/log/cassandra
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* sudo chown -R `whoami` /var/log/cassandra
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* sudo mkdir -p /var/lib/cassandra
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* sudo chown -R `whoami` /var/lib/cassandra
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First, we'll unpack our archive:
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Note: The sample configuration files in conf/ determine the file-system
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locations Cassandra uses for logging and data storage. You are free to
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change these to suit your own environment and adjust the path names
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used here accordingly.
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$ tar -zxvf apache-cassandra-$VERSION.tar.gz
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$ cd apache-cassandra-$VERSION
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Now that we're ready, let's start it up!
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and create the log and data directories. These correspond to the defaults from conf/ and may be adjusted to suit your own environment:
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* bin/cassandra -f
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$ sudo mkdir -p /var/log/cassandra
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$ sudo chown -R `whoami` /var/log/cassandra
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$ sudo mkdir -p /var/lib/cassandra
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$ sudo chown -R `whoami` /var/lib/cassandra
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Unix: Running the startup script with the -f argument will cause
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Cassandra to remain in the foreground and log to standard out.
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Finally, we start the server. Running the startup script with the -f argument will cause
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Cassandra to remain in the foreground and log to standard out; it can be stopped with ctrl-C.
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Windows: bin\cassandra.bat runs in the foreground by default. To
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install Cassandra as a Windows service, download Procrun from
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http://commons.apache.org/daemon/procrun.html, set the PRUNSRV
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environment variable to the full path of prunsrv (e.g.,
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$ bin/cassandra -f
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****
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Note for Windows users: to install Cassandra as a service, download
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Procrun from http://commons.apache.org/daemon/procrun.html, set the
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PRUNSRV environment variable to the full path of prunsrv (e.g.,
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C:\procrun\prunsrv.exe), and run "bin\cassandra.bat install".
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Similarly, "uninstall" will remove the service.
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****
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Now let's try to read and write some data using the Cassandra Query Language:
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* bin/cqlsh
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$ bin/cqlsh
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The command line client is interactive so if everything worked you should
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be sitting in front of a prompt...
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Connected to Test Cluster at localhost:9160.
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[cqlsh 2.2.0 | Cassandra 1.2.0 | CQL spec 3.0.0 | Thrift protocol 19.35.0]
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Use HELP for help.
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cqlsh>
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be sitting in front of a prompt:
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----
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Connected to Test Cluster at localhost:9160.
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[cqlsh 2.2.0 | Cassandra 1.2.0 | CQL spec 3.0.0 | Thrift protocol 19.35.0]
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Use HELP for help.
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cqlsh>
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----
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As the banner says, you can use 'help;' or '?' to see what CQL has to
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offer, and 'quit;' or 'exit;' when you've had enough fun. But lets try
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something slightly more interesting:
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cqlsh> CREATE SCHEMA schema1
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WITH replication = { 'class' : 'SimpleStrategy', 'replication_factor' : 1 };
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cqlsh> USE schema1;
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cqlsh:Schema1> CREATE TABLE users (
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user_id varchar PRIMARY KEY,
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first varchar,
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last varchar,
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age int
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);
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cqlsh:Schema1> INSERT INTO users (user_id, first, last, age)
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VALUES ('jsmith', 'John', 'Smith', 42);
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cqlsh:Schema1> SELECT * FROM users;
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user_id | age | first | last
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---------+-----+-------+-------
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jsmith | 42 | john | smith
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cqlsh:Schema1>
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----
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cqlsh> CREATE SCHEMA schema1
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WITH replication = { 'class' : 'SimpleStrategy', 'replication_factor' : 1 };
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cqlsh> USE schema1;
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cqlsh:Schema1> CREATE TABLE users (
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user_id varchar PRIMARY KEY,
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first varchar,
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last varchar,
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age int
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);
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cqlsh:Schema1> INSERT INTO users (user_id, first, last, age)
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VALUES ('jsmith', 'John', 'Smith', 42);
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cqlsh:Schema1> SELECT * FROM users;
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user_id | age | first | last
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---------+-----+-------+-------
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jsmith | 42 | john | smith
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cqlsh:Schema1>
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----
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If your session looks similar to what's above, congrats, your single node
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cluster is operational!
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For more on what commands are supported by CQL, see
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https://github.com/apache/cassandra/blob/trunk/doc/cql3/CQL.textile. A
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reasonable way to think of it is as, "SQL minus joins and subqueries."
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https://github.com/apache/cassandra/blob/trunk/doc/cql3/CQL.textile[the CQL reference]. A
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reasonable way to think of it is as, "SQL minus joins and subqueries, plus collections."
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Wondering where to go from here?
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