Thank-you so much for your quick response. Yea, the option is use only for hive-on-tez. I want to know its source， its principle. Mybe this resource “http://www.slideshare.net/Hadoop_Summit/w-235phall1pandey/29” is very useful, but I can not visit it in our country (mybe for political reasons). Can you please tell me other explainations?
Thankyou & Rest Regards ---LLBian At 2016-01-19 11:44:02, "Gopal Vijayaraghavan" <gop...@apache.org> wrote: > >>what is the difference between³hive.compute.splits.in.am=true²and >>"hive.compute.splits.in.am=false"? >>which value is better? > >First up, those options are specific to Tez. > >The old MapReduce model was to always compute splits before asking for >resources to run. And this uses the gateway host (where the CLI runs) to >do that. > >That model runs sequentially and overload single gateway machines during >heavy concurrency, particularly when used via ODBC (HiveServer2 mode). > >Here's an old slide explaining how that speeds up queries. > >http://www.slideshare.net/Hadoop_Summit/w-235phall1pandey/29 > > >This dynamic & pipelined model lays down the foundation for optimizations >like Tez's dynamic partition pruning. > >Cheers, >Gopal > >
