我使用的是sparksql2.4.1、spark-cassandra-connector_2.11-2.4.1.jar和java8。我有一个情况，为了审计的目的，我需要计算ctable的表行数。我的c表中有大约20亿条记录。
为了计算行数，我尝试了两种方法，如下所示。

public static Long getColumnFamilyCountJavaApi(SparkSession spark,String keyspace, String columnFamilyName)  throws IOException{
  JavaSparkContext sc = new JavaSparkContext(spark.sparkContext());
  return javaFunctions(sc).cassandraTable(keyspace, columnFamilyName).cassandraCount();
}

public static Long getColumnFamilyCount(SparkSession spark,String keyspace, String columnFamilyName)  throws IOException{
  return spark
              .read()
              .format("org.apache.spark.sql.cassandra")
              .option("table", columnFamilyName)
              .option("keyspace",keyspace )
              .load().count();
}

但两种方法都会导致相同的错误。

Caused by: com.datastax.driver.core.exceptions.ReadFailureException: Cassandra failure during read query at consistency LOCAL_QUORUM (2 responses were required but only 0 replica responded, 2 failed)
            at com.datastax.driver.core.exceptions.ReadFailureException.copy(ReadFailureException.java:85)
    com.datastax.driver.core.DefaultResultSetFuture.getUninterruptibly(DefaultResultSetFuture.java:245)
            at com.datastax.spark.connector.cql.DefaultScanner.scan(Scanner.scala:34)
            at com.datastax.spark.connector.rdd.CassandraTableScanRDD.com$datastax$spark$connector$rdd$CassandraTableScanRDD$$fetchTokenRange(CassandraTableScanRDD.scala:342)

如何处理这种情况？