ErlCassa is an Erlang client to the Cassandra Query Language (CQL). This is an alpha library which should not be used in production.
Cassandra originally went with a Thrift RPC-based API as a way to provide a common denominator that more idiomatic clients could build upon independently. However, this worked poorly in practice: raw Thrift is too low-level to use productively, and keeping pace with new API methods to support (for example) indexes in 0.7 or distributed counters in 0.8 is too much for many maintainers to keep pace with.
CQL, the Cassandra Query Language, addresses this by pushing all implementation details to the server; all the client has to know for any operation is how to interpret “resultset” objects. So adding a feature like counters just requires teaching the CQL parser to understand “column + N” notation; no client-side changes are necessary.
CQL specification can be read here: http://github.com/apache/cassandra/blob/trunk/doc/cql/CQL.textile
- You will need Apache Thrift >= 0.80 and Apache Cassandra >= 1.0.
The easiest way to install Thrift on your system is to:
- install MacPorts;
- Download and install Thrift dependencies using MacPorts by issuing the command:
$ sudo port install boost libevent pkgconfig- Download Apache Thrift, then compile and install it:
$ ./configure --prefix=/usr/local/ --with-boost=/opt/local --with-libevent=/opt/local \
--without-csharp --without-ruby --without-perl --without-haskell
$ make
$ sudo make install{ok, C} = erlcassa_client:connect("localhost", 9160).{result, ok} = erlcassa_client:cql_execute(C,
"CREATE KEYSPACE test1 WITH strategy_class = SimpleStrategy AND strategy_options:replication_factor = 1;"
).{result, ok} = erlcassa_client:cql_execute(C, "USE test1;").{result, ok} = erlcassa_client:cql_execute(C, "
CREATE COLUMNFAMILY testdata (
KEY int PRIMARY KEY,
text_field text,
ascii_field ascii,
bigint_field bigint,
blob_field blob,
boolean_field boolean,
counter_field counter,
decimal_field decimal,
double_field double,
float_field float,
timestamp_field timestamp,
uuid_field uuid,
varchar_field varchar,
varint_field varint);
").{result, ok} = erlcassa_client:cql_execute(C, "
INSERT INTO testdata (
KEY, text_field, ascii_field, bigint_field, blob_field, boolean_field,
decimal_field, double_field, float_field, timestamp_field, uuid_field,
varchar_field, varint_field
) VALUES (
123, 'text', 'ascii', 1234567890, 'aaaaaa', true,
42, 1.3513535135, 1.2345, 1324244361517000, 'f47ac10b-58cc-4372-a567-0e02b2c3d479',
'encoded', 13
);
").{result, {rows, Rows}} = erlcassa_client:cql_execute(C, "SELECT * FROM testdata", proplist).Column = erlcassa_client:get_column("KEY", Row).{result, ok} = erlcassa_client:cql_execute(C, "DROP COLUMNFAMILY testdata;").{result, ok} = erlcassa_client:cql_execute(C, "DROP KEYSPACE test1;").The MIT License (MIT)
Copyright (c) 2011, Roberto Ostinelli
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The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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