Protocol::CassandraCQL::Client - a minimal Cassandra CQL client
Protocol::CassandraCQL::Client
use Protocol::CassandraCQL::Client; use Protocol::CassandraCQL qw( CONSISTENCY_QUORUM ); my $cass = Protocol::CassandraCQL::Client->new( PeerHost => "localhost", Keyspace => "my-keyspace", ); my ( undef, $result ) = $cass->query( "SELECT v FROM numbers" ); foreach my $row ( $result->rows_hash ) { say "We have a number $row->{v}"; }
This subclass of IO::Socket::IP implements a client that can execute queries on a Cassandra CQL database. It is not intended as a complete client, is simply provides enough functionallity to test that the protocol handling is working, and is used to implement the bundled examples/cqlsh utility.
For a more complete client, see instead Net::Async::CassandraCQL.
Takes the following arguments in addition to those accepted by IO::Socket::IP:
Authentication credentials if required by the server.
If defined, selects the keyspace to USE after connection.
USE
If defined, sets the CQL protocol version that will be negotiated. If omitted will default to 1.
Sends a message with the given opcode and Protocol::CassandraCQL::Frame for the message body. Waits for a response to be received, and returns it.
If the response opcode is OPCODE_ERROR then the error message string is thrown directly as an exception; this method will only return in non-error cases.
OPCODE_ERROR
Performs a CQL query and returns the result, as decoded by "parse_result_frame" in Protocol::CassandraCQL::Frames.
For USE queries, the type is RESULT_SET_KEYSPACE and $result is a string giving the name of the new keyspace.
RESULT_SET_KEYSPACE
$result
For CREATE, ALTER and DROP queries, the type is RESULT_SCHEMA_CHANGE and $result is a 3-element ARRAY reference containing the type of change, the keyspace and the table name.
CREATE
ALTER
DROP
RESULT_SCHEMA_CHANGE
For SELECT queries, the type is RESULT_ROWS and $result is an instance of Protocol::CassandraCQL::Result containing the returned row data.
SELECT
RESULT_ROWS
For other queries, such as INSERT, UPDATE and DELETE, the method returns RESULT_VOID and $result is undef.
INSERT
UPDATE
DELETE
RESULT_VOID
undef
A convenient shortcut to the USE $keyspace query which escapes the keyspace name.
USE $keyspace
Consider how the server's maximum supported CQL version can be detected on startup. This is made hard by the fact that the server closes the connection if the version is too high, so we'll have to reconnect it.
This code was paid for by
Perceptyx http://www.perceptyx.com/
Shadowcat Systems http://www.shadow.cat
Paul Evans <leonerd@leonerd.org.uk>
To install Protocol::CassandraCQL, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Protocol::CassandraCQL
CPAN shell
perl -MCPAN -e shell install Protocol::CassandraCQL
For more information on module installation, please visit the detailed CPAN module installation guide.