Spark SQL datediff只需几秒钟

Question

我有以下代码:

table.select(datediff(table.col("Start Time"), table.col("End Time"))).show()

日期格式为2016-05-19 09:23:28(YYYY-MM-DD HH:mm:SS)

函数datediff计算天数的差异.但我想在几秒钟内有所不同.

Answer 1

您可以使用unix_timestamp()函数将日期转换为秒.

import org.apache.spark.sql.functions._

//For $ notation columns // Spark 2.0
import spark.implicits._

table.withColumn("date_diff", 
   (unix_timestamp($"Start Time") - unix_timestamp($"End Time"))
).show()

编辑:(根据评论)

UDF将秒数转换为HH:mm:ss

sqlContext.udf.register("sec_to_time", (s: Long) => 
   ((s / 3600L) + ":" + (s / 60L) + ":" + (s % 60L))
)

//Use registered UDF now
table.withColumn("date_diff", 
   sec_to_time(unix_timestamp($"Start Time") - unix_timestamp($"End Time"))
).show()