A Script for Dumping Data From Cassandra

To manage our database migrations for Cassandra, we've taken to creating scripts that create/modify the schema and populate configuration data. In my previous post, I showed how to dump and load the schema (keyspaces and column families).

Here is a code snippet that lets you dump the data into set statements that you can then load via the CLI.

     public void dumpColumnFamily() {  
         String columnFamily = "YOUR_COLUMN_FAMILY";  
         Cluster cluster = HFactory.getOrCreateCluster("dev", "localhost:9160");  
         Keyspace keyspace = HFactory.createKeyspace("YOUR_KEYSPACE", cluster);  
         RangeSlicesQuery<String, String, String> rangeSlicesQuery = HFactory  
                 .createRangeSlicesQuery(keyspace, StringSerializer.get(),  
                         StringSerializer.get(), StringSerializer.get());  
         rangeSlicesQuery.setColumnFamily(columnFamily);  
         rangeSlicesQuery.setKeys("", "");  
         rangeSlicesQuery.setRange("", "", false, 2000); // MAX_COLUMNS  
         rangeSlicesQuery.setRowCount(2000); // MAX_ROWS  
         QueryResult<OrderedRows<String, String, String>> result = rangeSlicesQuery .execute();  
         OrderedRows<String, String, String> orderedRows = result.get();  
         for (Row<String, String, String> r : orderedRows) {  
             ColumnSlice<String, String> slice = r.getColumnSlice();  
             for (HColumn<String, String> column : slice.getColumns()) {  
                 System.out.println("set " + columnFamily + "['" + r.getKey()  
                         + "']" + "['" + column.getName() + "'] = '"  
                         + column.getValue() + "';");  
             }  
         }  
     }