Hi All , I want to do a dataframe operation to find the rows having the latest timestamp in each group using the below operation
df.orderBy(desc("transaction_date")).groupBy("mobileno").agg(first("customername").as("customername"),first("service_type").as("service_type"),first("cust_addr").as("cust_abbr")) .select("customername","service_type","mobileno","cust_addr") *Spark Version :: 1.6.x* My Question is *"Will Spark guarantee the Order while doing the groupBy , if DF is ordered using OrderBy previously in Spark 1.6.x"??* *I referred a blog here :: **https://bzhangusc.wordpress.com/2015/05/28/groupby-on-dataframe-is-not-the-groupby-on-rdd/ <https://bzhangusc.wordpress.com/2015/05/28/groupby-on-dataframe-is-not-the-groupby-on-rdd/>* *Which claims it will work except in Spark 1.5.1 and 1.5.2 .* *I need a bit elaboration of how internally spark handles it ? also is it more efficient than using a Window function ?* *Thanks in Advance ,* *Rabin Banerjee*