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Paul Evans > Protocol-CassandraCQL > Protocol::CassandraCQL::Client



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Protocol::CassandraCQL::Client - a minimal Cassandra CQL 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.


$cass = Protocol::CassandraCQL::Client->new( %args )

Takes the following arguments in addition to those accepted by IO::Socket::IP:

Username => STRING
Password => STRING

Authentication credentials if required by the server.

Keyspace => STRING

If defined, selects the keyspace to USE after connection.

CQLVersion => INT

If defined, sets the CQL protocol version that will be negotiated. If omitted will default to 1.


( $result_op, $result_frame ) = $cass->send_message( $opcode, $frame )

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.

( $type, $result ) = $cass->query( $cql, $consistency )

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.

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.

For SELECT queries, the type is RESULT_ROWS and $result is an instance of Protocol::CassandraCQL::Result containing the returned row data.

For other queries, such as INSERT, UPDATE and DELETE, the method returns RESULT_VOID and $result is undef.

( $type, $result ) = $cass->use_keyspace( $keyspace )

A convenient shortcut to the USE $keyspace query which escapes the keyspace name.



This code was paid for by


Paul Evans <>

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