presto-cassandra/src/main/java/io/prestosql/plugin/cassandra/CassandraTokenSplitManager.java/CassandraTokenSplitManager/getTotalPartitionsCount
class CassandraTokenSplitManager:    public long getTotalPartitionsCount(String keyspace, String table, Optional<Long> sessionSplitsPerNode)
    {
        if (sessionSplitsPerNode.isPresent()) {
            return sessionSplitsPerNode.get();
        }
        if (configSplitsPerNode.isPresent()) {
            return configSplitsPerNode.get();
        }
        List<SizeEstimate> estimates = session.getSizeEstimates(keyspace, table);
        return estimates.stream()
                .mapToLong(SizeEstimate::getPartitionsCount)
                .sum();
    }