Examples with DBIterator org.iq80.leveldb.DBIterator used on opensource projects

Example 16 with DBIterator

use of org.iq80.leveldb.DBIterator in project cdap by caskdata.

the class LevelDBTableCore method deleteRows.

/**
   * Delete a list of rows from the table entirely, disregarding transactions.
   * @param toDelete the row keys to delete
   */
public void deleteRows(Collection<byte[]> toDelete) throws IOException {
    if (toDelete.isEmpty()) {
        return;
    }
    // find first row to delete and first entry in the DB to examine
    Iterator<byte[]> rows = toDelete.iterator();
    byte[] currentRow = rows.next();
    byte[] startKey = createStartKey(currentRow);
    DB db = getDB();
    WriteBatch batch = db.createWriteBatch();
    try (DBIterator iterator = db.iterator()) {
        iterator.seek(startKey);
        if (!iterator.hasNext()) {
            // nothing in the db to delete
            return;
        }
        Map.Entry<byte[], byte[]> entry = iterator.next();
        // iterate over the database and the rows to delete, collecting (raw) keys to delete
        while (entry != null && currentRow != null) {
            KeyValue kv = KeyValue.fromKey(entry.getKey());
            int comp = Bytes.compareTo(kv.getRow(), currentRow);
            if (comp == 0) {
                // same row -> delete
                batch.delete(entry.getKey());
                entry = iterator.hasNext() ? iterator.next() : null;
            } else if (comp > 0) {
                // read past current row -> move to next row
                currentRow = rows.hasNext() ? rows.next() : null;
            } else if (comp < 0) {
                // iterator must seek to current row
                iterator.seek(createStartKey(currentRow));
                entry = iterator.hasNext() ? iterator.next() : null;
            }
        }
    }
    // delete all the entries that were found
    db.write(batch, getWriteOptions());
}

Example 17 with DBIterator

use of org.iq80.leveldb.DBIterator in project cdap by caskdata.

the class LevelDBTableCore method getRow.

/**
   * if columns are not null, then limit param is ignored and limit is columns.length
   */
public NavigableMap<byte[], byte[]> getRow(byte[] row, @Nullable byte[][] columns, byte[] startCol, byte[] stopCol, int limit, Transaction tx) throws IOException {
    if (columns != null) {
        if (columns.length == 0) {
            return EMPTY_ROW_MAP;
        }
        columns = Arrays.copyOf(columns, columns.length);
        Arrays.sort(columns, Bytes.BYTES_COMPARATOR);
        limit = columns.length;
    }
    byte[] startKey = createStartKey(row, columns == null ? startCol : columns[0]);
    byte[] endKey = createEndKey(row, columns == null ? stopCol : upperBound(columns[columns.length - 1]));
    try (DBIterator iterator = getDB().iterator()) {
        iterator.seek(startKey);
        return getRow(iterator, endKey, tx, false, columns, limit).getSecond();
    }
}