Huilang,
Since there hasn't been another reply yet, I'll throw out an idea that worked for us as part of a test, though it does not seem exactly like a "preferred" way since it crosses code-bases. We built the type using straight java type, then used the Datastax v2 driver's DataType class serializer. Concretely, it would look like the following (adapting your code): Column column = new Column(); column.name<http://column.name>=columnSerializer.toByteBuffer(colname); // the column name of the map type, it works with other kinds of data type ?column.value = DataType.map(DataType.ascii, DataType.decimal).serialize(yourMapGoesHere); column.timestamp = new Date().getTime(); ... ________________________________ From: Huiliang Zhang <zhl...@gmail.com> Sent: Friday, June 20, 2014 10:10 PM To: user@cassandra.apache.org Subject: Use Cassnadra thrift API with collection type Hi, I have a problem when insert data of the map type into a cassandra table. I tried all kinds of MapSerializer to serialize the Map data and did not succeed. My code is like this: Column column = new Column(); column.name<http://column.name>=columnSerializer.toByteBuffer(colname); // the column name of the map type, it works with other kinds of data type column.value = MapSerializer.getInstance(AsciiSerializer.instance, DecimalSerializer.instance).serialize(someMapData); column.timestamp = new Date().getTime(); Mutation mutation = new Mutation(); mutation.column_or_supercolumn = new ColumnOrSuperColumn(); mutation.column_or_supercolumn.column = column; mutationList.add(mutation); The data was input into the cassandra DB however it cannot be retrieved by CQL3 with the following error: ERROR 14:32:48,192 Exception in thread Thread[Thrift:4,5,main] java.lang.AssertionError at org.apache.cassandra.cql3.statements.ColumnGroupMap.getCollection(ColumnGroupMap.java:88) at org.apache.cassandra.cql3.statements.SelectStatement.getCollectionValue(SelectStatement.java:1185) at org.apache.cassandra.cql3.statements.SelectStatement.handleGroup(SelectStatement.java:1169) at org.apache.cassandra.cql3.statements.SelectStatement.processColumnFamily(SelectStatement.java:1076) ... So the question is how to write map data into cassandra by thrift API. Appreciated for any help. Thanks, Huiliang