You should do joins using the ON clause. https://cwiki.apache.org/Hive/languagemanual-joins.html be careful if you do the joins wrong hive does a Cartesian product followed by a really long reduce phase rather then the optimal join process.
On Thu, Jan 12, 2012 at 6:04 PM, Aaron McCurry <amccu...@gmail.com> wrote: > I see that your query is kinda generic and probably not the original > query. I have seen this behavior with a simple typo like: > > Notice col3. > > create table z as select x.* from table1 x join table2 y where ( > x.col1 = y.col1 and > x.col2 = y.col2 and > y.col3 = y.col3 and > x.col4 = y.col4 and > x.col5 = y.col5 > ); > > Just a thought. > > Aaron > > On Thu, Jan 12, 2012 at 6:00 PM, Wojciech Langiewicz < > wlangiew...@gmail.com> wrote: > >> Hello, >> Have you tried running only select, without creating table? What are >> results? >> How did you tried to set number of reducers? Have you used this: >> set mapred.reduce.tasks = xyz; >> How many mappers does this query use? >> >> >> On 12.01.2012 23:53, Koert Kuipers wrote: >> >>> I am running a basic join of 2 tables and it will only run with 1 >>> reducer. >>> why is that? i tried to set the number of reducers and it didn't work. >>> hive >>> just ignored it. >>> >>> create table z as select x.* from table1 x join table2 y where ( >>> x.col1 = y.col1 and >>> x.col2 = y.col2 and >>> x.col3 = y.col3 and >>> x.col4 = y.col4 and >>> x.col5 = y.col5 >>> ); >>> >>> both tables are backed by multiple files / blocks / chunks >>> >>> >> -- >> Wojciech Langiewicz >> > >
