Yes, I tried that, it looks like it forces it to 1 if there are no groups. 2011/1/24 Ajo Fod <ajo....@gmail.com>
> oh ... sorry you say you already tried that. > > > > On Mon, Jan 24, 2011 at 1:54 PM, Ajo Fod <ajo....@gmail.com> wrote: > > you could try to set the number of reducers e.g: > > set mapred.reduce.tasks=4; > > > > set this before doing the select. > > > > -Ajo > > > > On Mon, Jan 24, 2011 at 1:13 PM, Jonathan Coveney <jcove...@gmail.com> > wrote: > >> I have a 10 node server or so, and have been mainly using pig on it, but > >> would like to try out Hive. > >> I am running this query, which doesn't take too long in Pig, but is > taking > >> quite a long time in Hive. > >> > >> hive -e "select count(1) as ct from my_table where v1='02' and v2 = > >> 11112222;" > thecount > >> One thing is that this job only uses 1 reducer, but it is taking most of > its > >> time in its reduce step. I tried manually setting more reducers, but I > think > >> that for a job without groups, it forces 1 reducer? > >> Either way, would love to know why this is dragging? It's worth noting > that > >> my_table is not saved in the Hive format, but rather as a flat file. I > >> realize that this can influence performance, but shouldn't it at least > >> perform on par with pig? > >> Thanks for your help > >> Jon > > >
