How to apply lag function on streaming dataframe?

问题

I have a streaming dataframe having three columns time,col1,col2. I have to apply lag function on column2. I have tried following query.

val w = org.apache.spark.sql.expressions.Window.oderBy("time")
df.select(col("time"),col("col1"),lag("col3",1).over(w))

But It gives following exception

org.apache.spark.sql.AnalysisException: Non-time-based windows are not supported on streaming DataFrames/Datasets

How can i achieve this?

Thanks in advance.

来源：https://stackoverflow.com/questions/46036845/how-to-apply-lag-function-on-streaming-dataframe