// We can't simply use incrementColumnValue here because the timestamp of
// the keyvalue will not be changed as long as it remains in memstore, so
// there will be some unavoidable contention on the row if multiple
// Stargate instances are concurrently serving the same user, and three
// more round trips than otherwise.
RowLock rl = table.lockRow(row);
try {
Get get = new Get(row, rl);
get.addColumn(USER, TOKENS);
List<KeyValue> kvs = table.get(get).list();
if (kvs != null && !kvs.isEmpty()) {