This driver uses the old Thrift protocol, if you are using Cassandra 1.2 or higher and you are using CQL, please consider using node-cassandra-cql. While I will continue to fix bugs with this driver, feature development is frozen as many new features coming out will not be supported by Thrift.
NodeJS Bindings for Cassandra
Currently the driver has full CQL support and a growing support for thrift (non-cql) commands. If you would like to contribute, please contact Russ Bradberry <rbradberry@simplereach.com>
If you have any questions regarding the driver, please visit our google group
npm install helenus
Ensure cassandra is running on localhost:9160.
make test
For coverage
make test-cov
var helenus = require('helenus'),
pool = new helenus.ConnectionPool({
hosts : ['localhost:9160'],
keyspace : 'helenus_test',
user : 'test',
password : 'test1233',
timeout : 3000
//cqlVersion : '3.0.0' // specify this if you're using Cassandra 1.1 and want to use CQL 3
});
//optionally you can supply the 'getHost' parameter to the connection pool options which will
// allow you to override the default random host decision
//if you don't listen for error, it will bubble up to `process.uncaughtException`
//pools act just like connection objects, so you don't have to worry about api
//differences when using either the pool or the connection
pool.on('error', function(err){
console.error(err.name, err.message);
});
//makes a connection to the pool, this will return once there is at least one
//valid connection, other connections may still be pending
pool.connect(function(err, keyspace){
if(err){
throw(err);
} else {
//to use cql, access the pool object once connected
//the first argument is the CQL string, the second is an `Array` of items
//to interpolate into the format string, the last is the callback
//for formatting specific see `http://nodejs.org/docs/latest/api/util.html#util.format`
//results is an array of row objects
pool.cql("SELECT col FROM cf_one WHERE key = ?", ['key123'], function(err, results){
console.log(err, results);
});
//NOTE:
//- You can always skip quotes around placeholders, they are added automatically.
//- In CQL 3 you cannot use placeholders for ColumnFamily names or Column names.
}
});If you do not want to use CQL, you can make calls using the thrift driver
pool.connect(function(err, keyspace){
if(err){
throw(err);
}
//first retreive the column family from the server
//helenus will cache column families it has already seen
keyspace.get('my_cf', function(err, cf){
if(err){
throw(err);
}
//insert something into the column family
cf.insert('foo', {'bar':'baz'}, function(err){
if(err){
throw(err);
}
//get what we just put in
//the driver will return a helenus.Row object just like CQL
cf.get('foo', {consistency:helenus.ConsistencyLevel.ONE}, function(err, row){
if(err){
throw(err);
}
row.get('bar').value // => baz
});
});
});
});Currently Helenus supports the following command for the thrift side of the driver:
- connection.createKeyspace
- connection.dropKeyspace
- keyspace.createColumnFamily
- keyspace.dropColumnFamily
- columnFamily.insert
- columnFamily.get
- columnFamily.getIndexed
- columnFamily.remove
- columnFamily.truncate
The following support is going to be added in later releases:
- columnFamily.rowCount
- columnFamily.columnCount
- columnfamily.increment
- SuperColumns
- CounterColumns
- Better composite support
The Helenus Row object acts like an array but contains some helper methods to make your life a bit easier when dealing with dynamic columns in Cassandra
Returns the number of columns in the row
This will return the column at index N
results.forEach(function(row){
//gets the 5th column of each row
console.log(row[5]);
});
This will return the column with a specific name
results.forEach(function(row){
//gets the column with the name 'foo' of each row
console.log(row.get('foo'));
});
This is wrapper function of Array.forEach which return name,value,ts,ttl of column from row as callback params.
results.forEach(function(row){
//all row of result
row.forEach(function(name,value,ts,ttl){
//all column of row
console.log(name,value,ts,ttl);
});
});
Slices columns in the row based on their numeric index, this allows you to get columns x through y, it returns a Helenus row object of columns that match the slice.
results.forEach(function(row){
//gets the first 5 columns of each row
console.log(row.slice(0,5));
});
Slices the columns based on part of their column name. returns a Helenus row of columns that match the slice
results.forEach(function(row){
//gets all columns that start with a, b, c, or d
console.log(row.nameSlice('a','e'));
});
Columns are returned as objects with the following structure:
{
name: 'Foo', //The column name
value: 'bar', //The column value
timestamp: Date(), //The date object of the timestamp for the column
ttl: 123456 //The ttl (in milliseconds) for the columns
}Helenus supports using a custom consistency level. By default, when using the thrift client reads and writes will both use QUORUM. When using the thrift driver, you simply pass a custom level in the options:
cf.insert(key, values, {consistency : helenus.ConsistencyLevel.ANY}, callback);- Russell Bradberry - @devdazed
- Matthias Eder - @matthiase
- Christoph Tavan - @ctavan
(The MIT License)
Copyright (c) 2011 SimpleReach <rbradberry@simplereach.com>
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