Spark Sql映射问题

Question

sparks 2/Java8 8 Cassandra2试图读取Cassandra中的一些数据，然后在sparks中按查询运行组。在DF传输日期(日期)、原点(字符串)中只有2列。

Dataset<Row> maxOrigindate = sparks.sql("SELECT origin, transdate, COUNT(*) AS cnt FROM origins  GROUP BY (origin,transdate) ORDER BY cnt DESC LIMIT 1"); `

获取错误：

 `Exception in thread "main" org.apache.spark.sql.AnalysisException: expression 'origins.`origin`' is neither present in the group by, nor is it an aggregate function. Add to group by or wrap in first() (or first_value)`

已解决按问题分组删除()的问题如下

完整代码：(试图获得最大的传输日期的原点/位置)

JavaRDD<TransByDate> originDateRDD = javaFunctions(sc).cassandraTable("trans", "trans_by_date", CassandraJavaUtil.mapRowTo(TransByDate.class))
                    .select(CassandraJavaUtil.column("origin"), CassandraJavaUtil.column("trans_date").as("transdate")).limit((long)100) ;
Dataset<Row> originDF = sparks.createDataFrame(originDateRDD, TransByDate.class);
String[] columns = originDF.columns();
System.out.println("originDF columns: "+columns[0]+" "+columns[1]) ; -> transdate origin
originDF.createOrReplaceTempView("origins");

Dataset<Row> maxOrigindate = sparks.sql("SELECT origin, transdate, COUNT(*) AS cnt FROM origins  GROUP BY origin,transdate ORDER BY cnt DESC LIMIT 1"); 
List list = maxOrigindate.collectAsList(); -> Exception here
int j = list.size();

originDF 列：传输原点

`public static class TransByDate implements Serializable {
        private String origin;
        private Date transdate;

        public TransByDate() { }

        public TransByDate (String origin, Date transdate) { 
            this.origin = origin;
            this.transdate= transdate;

        }

        public String getOrigin() { return origin; }
        public void setOrigin(String origin) { this.origin = origin; }

        public Date getTransdate() { return transdate; }
        public void setTransdate(Date transdate) { this.transdate = transdate; }

    }

模式

root
 |-- transdate: struct (nullable = true)
 |    |-- date: integer (nullable = false)
 |    |-- day: integer (nullable = false)
 |    |-- hours: integer (nullable = false)
 |    |-- minutes: integer (nullable = false)
 |    |-- month: integer (nullable = false)
 |    |-- seconds: integer (nullable = false)
 |    |-- time: long (nullable = false)
 |    |-- timezoneOffset: integer (nullable = false)
 |    |-- year: integer (nullable = false)
 |-- origin: string (nullable = true)

org.apache.spark.sql.catalyst.CatalystTypeConverters$StructConverter.toCatalystImpl(CatalystTypeConverters.scala:256) org.apache.spark.sql.catalyst.CatalystTypeConverters$StructConverter.toCatalystImpl(CatalystTypeConverters.scala:251) at org.apache.spark.sql.catalyst.CatalystTypeConverters$CatalystTypeConverter.toCatalyst(CatalystTypeConverters.scala:103) .的异常错误执行器:任务0.0中的异常(TID 12) scala.MatchError: Sun Jan 01 00:00:00 PST 2012 (类java.util.Date)。线程"main“org.apache.spark.SparkException中的异常:由于阶段失败而中止作业:第2.0阶段中的任务0失败1次，最近一次失败:在阶段2.0中丢失任务0.0 (TID 12，localhost)：scala.MatchError: SunJan01 00:00:00 :00PST 2012 (java.util.Date类)司机追踪: org.apache.spark.scheduler.DAGScheduler.org$apache$spark$scheduler$DAGScheduler$$failJobAndIndependentStages(DAGScheduler.scala:1454) at org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1442) at org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1441) ..。在org.apache.spark.sql.Dataset$$anonfun$collectAsList$1.apply(Dataset.scala:2184) at org.apache.spark.sql.Dataset.withCallback(Dataset.scala:2559) at org.apache.spark.sql.Dataset.collectAsList(Dataset.scala:2184) at spark.SparkTest.sqlMaxCount(SparkTest.java:244) -> List = maxOrigindate.collectAsList();

致因：scala.MatchError：Sun Jan 01 00:00:00 PST 2012 ( class java.util.Date) at org.apache.spark.sql.catalyst.CatalystTypeConverters$StructConverter.toCatalystImpl(CatalystTypeConverters.scala:251) at org.apache.spark.sql.catalyst.CatalystTypeConverters$StructConverter.toCatalystImpl(CatalystTypeConverters.scala:251)

Answer 1

你的错误越来越少。

Caused by: scala.MatchError: Sun Jan 01 00:00:00 PST 2012 (of class java.util.Date) at 

此错误是因为Spark支持java.sql.Date类型。请查看星火文档这里。您还可以参考火花-2562。

Answer 2

将查询更改为

Dataset<Row> maxOrigindate = sparks.sql("SELECT origin, 
transdate, 
COUNT(*) AS cnt FROM origins  GROUP BY origin,transdate 
ORDER BY cnt DESC LIMIT 1"); 

这会管用的。