code: private Iterator<Record> rowQuery(DeltaPlacement placement,
                                        List<Map.Entry<ByteBuffer, Key>> keys,
                                        ReadConsistency consistency) {
          // Build the list of row IDs to query for.
          List<ByteBuffer> rowIds = Lists.transform(keys, entryKeyFunction());
  
          // Query for Delta & Compaction info, just the first 50 columns for now.
          final Rows<ByteBuffer, DeltaKey> rows = execute(placement.getKeyspace()
                          .prepareQuery(placement.getBlockedDeltaColumnFamily(), SorConsistencies.toAstyanax(consistency))
                          .getKeySlice(rowIds)
                          .withColumnRange(_maxColumnsRange),
                  "query %d keys from placement %s", rowIds.size(), placement.getName());
  
          // Track metrics
          _randomReadMeter.mark(rowIds.size());
  
          // Return an iterator that decodes the row results, avoiding pinning multiple decoded rows into memory at once.
          return decodeRows(keys, rows, _maxColumnsRange.getLimit(), consistency);
      }
docs: Queries for rows given an enumerated list of Cassandra row keys.