see https://issues.apache.org/jira/browse/NIFI-6407 ... View more

@Sandeep SIngh No, hive doesn't maintain any lock history. show locks; Above command would help you to get the user who has acquired a lock over the table in hive. But however if the lock is released then you will not be able to see the user who has acquired the locks. Also there is no history of locks being recorded as it is not necessarily needed for the namenode for any computation. Hope it helps! ... View more

Hi @Sandeep SIngh, Each mapper and reducer is a java process and we need some reserve memory to store the java code. Hence the Map/Reducer memory should be greater than the JVM heap size. ... View more

Its good approach but the only point which I could find as disadvantage is multiple hops to achieve the desired result. Instead of performing joins we can apply windowing function to achieve the same in a single hop assuming you unique value column and last modified date in your scenario. ... View more