我一直在搜索，但没有找到一个解决方案，即如何使用 Spark SQL 从纪元查询存储为 UTC 毫秒的日期。我从 NoSQL 数据源（来自 MongoDB 的 JSON）中提取的模式的目标日期为：
|-- dateCreated: struct (nullable = true)
||-- $date: long (nullable = true)
完整的架构如下：
scala> accEvt.printSchema
root
|-- _id: struct (nullable = true)
| |-- $oid: string (nullable = true)
|-- appId: integer (nullable = true)
|-- cId: long (nullable = true)
|-- data: struct (nullable = true)
| |-- expires: struct (nullable = true)
| | |-- $date: long (nullable = true)
| |-- metadata: struct (nullable = true)
| | |-- another key: string (nullable = true)
| | |-- class: string (nullable = true)
| | |-- field: string (nullable = true)
| | |-- flavors: string (nullable = true)
| | |-- foo: string (nullable = true)
| | |-- location1: string (nullable = true)
| | |-- location2: string (nullable = true)
| | |-- test: string (nullable = true)
| | |-- testKey: string (nullable = true)
| | |-- testKey2: string (nullable = true)
|-- dateCreated: struct (nullable = true)
| |-- $date: long (nullable = true)
|-- id: integer (nullable = true)
|-- originationDate: struct (nullable = true)
| |-- $date: long (nullable = true)
|-- processedDate: struct (nullable = true)
| |-- $date: long (nullable = true)
|-- receivedDate: struct (nullable = true)
| |-- $date: long (nullable = true)
我的目标是按照以下方式编写查询：
SELECT COUNT(*) FROM myTable WHERE dateCreated BETWEEN [dateStoredAsLong0] AND [dateStoredAsLong1]
到目前为止，我的过程是：
scala> val sqlContext = new org.apache.spark.sql.SQLContext(sc)
sqlContext: org.apache.spark.sql.SQLContext = org.apache.spark.sql.SQLContext@29200d25
scala> val accEvt = sqlContext.jsonFile("/home/bkarels/mongoexport/accomplishment_event.json")
...
14/10/29 15:03:38 INFO SparkContext: Job finished: reduce at JsonRDD.scala:46, took 4.668981083 s
accEvt: org.apache.spark.sql.SchemaRDD =
SchemaRDD[6] at RDD at SchemaRDD.scala:103
scala> accEvt.registerAsTable("accomplishmentEvent")
（此时下面的基线查询执行成功）
scala> sqlContext.sql("select count(*) from accomplishmentEvent").collect.foreach(println)
...
[74475]
现在，我无法正确理解的巫术是如何形成我的选择语句来推理日期。例如，以下执行无错误，但返回零而不是所有记录的计数（74475）。
scala> sqlContext.sql("select count(*) from accomplishmentEvent where processedDate >= '1970-01-01'").collect.foreach(println)
...
[0]
我也尝试过一些丑陋的东西，比如：
scala> val now = new java.util.Date()
now: java.util.Date = Wed Oct 29 15:05:15 CDT 2014
scala> val today = now.getTime
today: Long = 1414613115743
scala> val thirtydaysago = today - (30 * 24 * 60 * 60 * 1000)
thirtydaysago: Long = 1416316083039
scala> sqlContext.sql("select count(*) from accomplishmentEvent where processedDate <= %s and processedDate >= %s".format(today,thirtydaysago)).collect.foreach(println)
按照建议，我选择了一个命名字段以确保其有效。所以：
scala> sqlContext.sql("select receivedDate from accomplishmentEvent limit 10").collect.foreach(println)
返回：
[[1376318850033]]
[[1376319429590]]
[[1376320804289]]
[[1376320832835]]
[[1376320832960]]
[[1376320835554]]
[[1376320914480]]
[[1376321041899]]
[[1376321109341]]
[[1376321121469]]
然后扩展以尝试使我尝试过的某些日期起作用：
scala> sqlContext.sql("select cId from accomplishmentEvent where receivedDate.date > '1970-01-01' limit 5").collect.foreach(println)
导致错误：
java.lang.RuntimeException: No such field date in StructType(ArrayBuffer(StructField($date,LongType,true)))
...
在我们的字段名称前面加上$同样建议的前缀会导致另一种错误：
scala> sqlContext.sql("select cId from accomplishmentEvent where receivedDate.$date > '1970-01-01' limit 5").collect.foreach(println)
java.lang.RuntimeException: [1.69] failure: ``UNION'' expected but ErrorToken(illegal character) found
select actualConsumerId from accomplishmentEvent where receivedDate.$date > '1970-01-01' limit 5
显然我不知道如何选择以这种方式存储的日期 - 谁能帮我填补这个空白？
我对 Scala 和 Spark 都比较陌生，所以如果这是一个基本问题，请原谅我，但我在论坛和 Spark 文档上的搜索结果为空。
谢谢你。