The columns are stored at the intersection of the row and the CF. So if you read all the columns for a row in a CF you are only getting those ones.
Your hector code (using the range) looks correct to me. Have fun. Aaron ----------------- Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 23/01/2012, at 9:24 PM, Tamar Fraenkel wrote: > Hi! > I am getting started with Cassandra and Hector and have a question. > If I have CF with many columns, only a small portion of them having values > for any given key. I want to read all columns for a given key, but I don't > know which columns were populated. > I managed to do that with the code below (assumes that column names are > incremental numbers). > Is there any better way? > Thanks, > Tamar > > private static void readAllColunsForRowKey(String key) { > MultigetSliceQuery<String, Long, String> multigetSlicesQuery = > HFactory.createMultigetSliceQuery(tutorialKeyspace, > StringSerializer.get(), LongSerializer.get(), > > StringSerializer.get()); > multigetSlicesQuery.setColumnFamily(CF); > multigetSlicesQuery.setKeys(key); > multigetSlicesQuery.setRange(null, null, false, COL_COUNT); > QueryResult<Rows<String, Long, String>> results = > multigetSlicesQuery.execute(); > Long lastColName; > while ((lastColName = printColsAndGetLastColName(results, key)) != null) { > multigetSlicesQuery.setRange(lastColName + 1, null, false, COL_COUNT); > results = multigetSlicesQuery.execute(); > } > } > > private static Long printColsAndGetLastColName(QueryResult<Rows<String, Long, > String>> results, String key) { > Rows<String, Long, String> rows = results.get(); > if (rows.getCount() != 1) { > System.out.println("No such key"); > return null; > } > Row<String, Long, String> row = rows.getByKey(key); > ColumnSlice<Long, String> columnSlice = row.getColumnSlice(); > List<HColumn<Long, String>> columns = columnSlice.getColumns(); > for (HColumn<Long, String> column : columns) { > System.out.println("Column Name: " + column.getName() > + ", Column Val: " + column.getValue()); > } > if (columns.size() == COL_COUNT) { > return columns.get(COL_COUNT - 1).getName(); > } > return null; > } >
