This affected us as well. Here are some potentially related bugs. My understanding of the internals is that it is doing a full table refresh. If you are doing LOAD DATA with partition, ideally it would only do an incremental refresh instead of full and you would get closer to flat times.   https://issues.apache.org/jira/browse/IMPALA-7330 https://issues.apache.org/jira/browse/IMPALA-7854   What version of Impala are you using? ... View more