/**
* Create a column batch and fetch the first set of columns using the given predicate. If no
* columns are found for the given row key and slice predicate, the first call to {@link
* #hasNext()} will return false.
*
* @param thisConn {@link DBConn} that provides the connection to perform the fetch. It also tells
* us what keyspace to use for subsequent column slices.
* @param columnParent Defines the column family to fetch columns from.
* @param rowKey Row of key to fetch columns from.
* @param slicePredicate Predicate that defines which columns to select.
*/
public CassandraColumnBatch(
DBConn thisConn, ColumnParent columnParent, byte[] rowKey, SlicePredicate slicePredicate) {
m_keyspace = thisConn.getKeyspace();
m_columnParent = columnParent;
m_rowKey = rowKey;
List<ColumnOrSuperColumn> columns =
thisConn.getSlice(m_columnParent, slicePredicate, ByteBuffer.wrap(m_rowKey));
m_sliceSize = 0;
m_iColumns = columns.iterator();
if (!m_iColumns.hasNext()) {
// tombstone? no columns to iterate
return;
}
// The slice is not empty, so we can simply get the first column
shiftColumn();
} // constructor
