I am executing this query:
INSERT OVERWRITE TABLE B SELECT * from A;
Table A has 6TB of data, i have changed mem_limit config to 70%.
Are there any other configuration changes to be made since the above query hangs when executed.
The first step to resolving hanging queries is to figure out why they are hanging.
1. Check the logs of the impalad you connect to. Often it will write details of what its doing. At the very least, we'll know which step hangs.
2. You can also check the Impala UI for more information about the query and its plan: http://impalad-node-hostname:25000
3. Are you sure its hanging and not just slow? Do you see the cluster using disks, CPU, etc? That can be a useful clue.
Using this information you may figure out what's going on. Or you can post extra information here and we can help more.