TIA if anyone can point me in the right direction on this. I'm running a simple Hive query (a count on an external table comprising 436 files, each of ~2GB). The cluster's mapred-site.xml specifies mapred.tasktracker.map.tasks.maximum = 7 - that is, 7 mappers per worker node. When I run regular MR jobs via "bin/hadoop jar myJob.jar...", I see 7 mappers spawned on each worker.
The problem: When I run my Hive query, I see 2 mappers spawned per worker. When I do "set -v;" from the Hive command line, I see mapred.tasktracker.map.tasks.maximum = 7. The job.xml for the Hive query shows mapred.tasktracker.map.tasks.maximum = 7. The only lead I have is that the default for mapred.tasktracker.map.tasks.maximum is 2, and even though it's overridden in the cluster's mapred-site.xml I've tried redundanltly overriding this variable everyplace I can think of (Hive command line with "-hiveconf", using set from the Hive prompt, et al) and nothing works. I've combed the docs & mailing list, but haven't run across the answer. Does anyone have any ideas what (if anything) I'm missing? Is this some quirk of Hive, where it decides that 2 mappers per tasktracker is enough, and I should just leave it alone? Or is there some knob I can fiddle to get it to use my cluster at full power? Many thanks in advance, - Brad -- Brad Heintz [email protected]
