Hi All, Following on from from our parquet vs orc discussion, today I observed hive's alter table ... concatenate command remove rows from an ORC formatted table.
1. Has anyone else observed this (fuller description below)? And 2. How to do parquet users handle the file fragmentation issue? Description of the problem: Today I ran a query to count rows by date. Relevant days below: 2016-02-28 16866 2016-03-06 219 2016-03-07 2863 I then ran concatenation on that table. Rerunning the same query resulted in: 2016-02-28 16866 2016-03-06 219 2016-03-07 1158 Note reduced count for 2016-03-07 I then ran concatenation a second time, and the query a third time: 2016-02-28 16344 2016-03-06 219 2016-03-07 1158 Now the count for 2016-02-28 is reduced. This doesn't look like an elimination of duplicates occurring by design - these didn't all happen on the first run of concatenation. It looks like concatenation just kind of loses data. -- Want to work at Handy? Check out our culture deck and open roles <http://www.handy.com/careers> Latest news <http://www.handy.com/press> at Handy Handy just raised $50m <http://venturebeat.com/2015/11/02/on-demand-home-service-handy-raises-50m-in-round-led-by-fidelity/> led by Fidelity
