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這種感覺有點愚蠢,但我正在從Spark 1.6.1遷移到Spark 2.0.2。我正在使用Databrick CSV庫,現在正試圖使用內置的CSV DataFrameWriter
。Spark 2.0.2似乎並不認爲「groupBy」正在返回一個DataFrame
下面的代碼:
// Get an SQLContext
val sqlContext = new SQLContext(sc)
import sqlContext.implicits._
var sTS = lTimestampToSummarize.toString()
val sS3InputPath = "s3://measurements/" + sTS + "/*"
// Read all measurements - note that all subsequent ETLs will reuse dfRaw
val dfRaw = sqlContext.read.json(sS3InputPath)
// Filter just the user/segment timespent records
val dfSegments = dfRaw.filter("segment_ts <> 0").withColumn("views", lit(1))
// Aggregate views and timespent per user/segment tuples
val dfUserSegments : DataFrame = dfSegments.groupBy("company_id", "division_id", "department_id", "course_id", "user_id", "segment_id")
.agg(sum("segment_ts").alias("segment_ts_sum"), sum("segment_est").alias("segment_est_sum"), sum("views").alias("segment_views"))
// The following will write CSV files to the S3 bucket
val sS3Output = "s3://output/" + sTS + "/usersegment/"
dfUserSegments.write.csv(sS3Output)
返回此錯誤:
[error] /home/Spark/src/main/scala/Example.scala:75: type mismatch;
[error] found : Unit
[error] required: org.apache.spark.sql.DataFrame
[error] (which expands to) org.apache.spark.sql.Dataset[org.apache.spark.sql.Row]
[error] dfUserSegments.write.csv(sS3Output)
[error] ^
[error] one error found
[error] (compile:compile) Compilation failed
[error] Total time: 2 s, completed Jun 5, 2017 5:00:12 PM
我知道我必須要解釋的錯誤錯誤的,因爲我設置dfUserSegments
明確是DataFrame
,然而編譯器告訴我它是Unit
(沒有類型)。
任何幫助表示讚賞。