Wouldn't you be better to delegate the compression part to Cassandra (which support Snappy [1])? This way the compression part will be completely transparent to your application.
[1] http://www.datastax.com/dev/blog/whats-new-in-cassandra-1-0-compression On Tue, Jan 28, 2014 at 8:51 PM, Check Peck <comptechge...@gmail.com> wrote: > I am working on a project in which I am supposed to store the snappy > compressed data in Cassandra, so that when I retrieve the same data from > Cassandra, it should be snappy compressed in memory and then I will > decompress that data using snappy to get the actual data from it. > > I am having a byte array in `bytesToStore` variable, then I am snappy > compressing it using google `Snappy` and stored it back into Cassandra - > > // .. some code here > System.out.println(bytesToStore); > > byte[] compressed = Snappy.compress(bytesToStore); > > attributesMap.put("e1", compressed); > > ICassandraClient client = CassandraFactory.getInstance().getDao(); > // write to Cassandra > client.upsertAttributes("0123", attributesMap, "sample_table"); > > After inserting the data in Cassandra, I went back into CQL mode and I > queried it and I can see this data in my table for the test_id `0123`- > > cqlsh:testingks> select * from sample_table where test_id = '0123'; > > test_id | name | value > > ---------+-------------+------------------------------------------------------------------------------------------------ > 0123 | e1 | > 0x2cac7fff0000012c4ebb95550000001e42797465204172726179205465737420466f722042696720456e6469616e > > > Now I am trying to read the same data back from Cassandra and everytime it > is giving me `IllegalArgumentException` - > > public Map<String, byte[]> getDataFromCassandra(final String rowKey, > final Collection<String> attributeNames) { > > Map<String, byte[]> dataFromCassandra = new > ConcurrentHashMap<String, byte[]>(); > > try { > String query="SELECT test_id, name, value from sample_table > where test_id = '"+rowKey+ "';"; > //SELECT test_id, name, value from sample_table where test_id > = '0123'; > System.out.println(query); > > DatastaxConnection.getInstance(); > > ResultSet result = > DatastaxConnection.getSession().execute(query); > > Iterator<Row> it = result.iterator(); > > while (it.hasNext()) { > Row r = it.next(); > for(String str : attributeNames) { > ByteBuffer bb = r.getBytes(str); // this line is > throwing an exception for me > byte[] ba=new byte[bb.remaining()]; > bb.get(ba, 0, ba.length); > dataFromCassandra.put(str, ba); > } > } > } catch (Exception e) { > e.printStackTrace(); > } > > return dataFromCassandra; > } > > This is the Exception I am getting - > > java.lang.IllegalArgumentException: e1 is not a column defined in this > metadata > > In the above method, I am passing rowKey as `0123` and `attributeNames` > contains `e1` as the string. > > I am expecting Snappy Compressed data in `dataFromCassandra` Map. In this > map the key should be `e1` and the value should be snappy compressed data > if I am not wrong.. And then I will iterate this Map to snappy decompress > the data.. > > I am using Datastax Java client working with Cassandra 1.2.9. > > Any thoughts what wrong I am doing here? > > To unsubscribe from this group and stop receiving emails from it, send an > email to java-driver-user+unsubscr...@lists.datastax.com. > -- :- a) Alex Popescu Sen. Product Manager @ DataStax @al3xandru
