TestDelete.java

public int removeAllOlderThan(int batchSize, DateTime date) {
        try (Connection c = dc.getConnection()) {
            PreparedStatement s1 = c.prepareStatement(String.format("SELECT %s FROM %s WHERE created_at < ?",
                    KEY, dc.getTableName(tableName)));
            s1.setLong(1, date.getMillis());
            ResultSet rs = s1.executeQuery();
            List<String> list = new ArrayList<>(batchSize);
            PreparedStatement s2 = null;
            int executeUpdateCount = 0;
            while (true) {
                list.clear();
                for (int i = 0; i < batchSize; i++) {
                    if (!rs.next())
                        break;
                    list.add(rs.getString(1));
                }
                if (list.isEmpty())
                    return executeUpdateCount;

                if (s2 == null || list.size() < batchSize)
                    s2 = c.prepareStatement(String.format("DELETE FROM %s WHERE %s IN (%s)",
                            dc.getTableName(tableName), KEY, buildParams(Math.min(list.size(), batchSize))));

                for (int i = 0; i < list.size(); i++) {
                    s2.setString(i + 1, list.get(i));
                }
                executeUpdateCount += s2.executeUpdate();
            }
        } catch (SQLException ex2) {
            throw new IllegalStateException(ex2);
        }
}


static String buildParams(int params) {
        if (params == 0)
            throw new IllegalArgumentException("0 or negative param count not expected");

        StringBuilder query = new StringBuilder();
        int currentCount = 0;
        for (; currentCount < params; currentCount++) {
            if (currentCount > 0)
                query.append(',');
            query.append('?');
        }
        return query.toString();
}