columns = Arrays.copyOf(columns, columns.length);
Arrays.sort(columns, Bytes.BYTES_COMPARATOR);
}
DB db = getDB();
DBIterator iterator = db.iterator();
seekToStart(iterator, startRow);
byte[] endKey = stopRow == null ? null : createEndKey(stopRow);
Scanner scanner = new LevelDBScanner(iterator, endKey, filter, columns, null);
DBIterator deleteIterator = db.iterator();
seekToStart(deleteIterator, startRow);
final int deletesPerRound = 1024; // todo make configurable
try {
Row rowValues;
WriteBatch batch = db.createWriteBatch();
int deletesInBatch = 0;
// go through all matching cells and delete them in batches.
while ((rowValues = scanner.next()) != null) {
byte[] row = rowValues.getRow();
for (byte[] column : rowValues.getColumns().keySet()) {
addToDeleteBatch(batch, deleteIterator, row, column);
deletesInBatch++;
// perform the deletes when we have built up a batch.
if (deletesInBatch >= deletesPerRound) {
// delete all the entries that were found
db.write(batch, getWriteOptions());
batch = db.createWriteBatch();
deletesInBatch = 0;
}
}
}
// perform any outstanding deletes
if (deletesInBatch > 0) {
db.write(batch, getWriteOptions());
}
} finally {
scanner.close();
deleteIterator.close();
}
}