Hi Bhavesh, [moving discussion to hive user list]
I would suggest you to send your discussion to hive user list in order to reach a broader audience. As per my understanding, in the query- map_script and reduce_script are custom scripts that run as a streaming jobs. You are asking hive to run map_script as mapper job on 3 columns to generate 3 new values- c1, c2, c3. After this, hive will sort your records on c1 and c2 and distribute them to reducers based on c3 values. 'reduce_scripts' will consume these 3 records and generate 2 records to store in pv_users_reduced. Hope it helps. Thanks, Aniket On Wed, Jan 4, 2012 at 8:55 PM, Bhavesh Shah <bhavesh25s...@gmail.com>wrote: > Hello, > I am new to hive. I want to write block of queries in Hive so that one > query give result to another one like in SQL. > > I have also visited one link given below: > http://karmasphere.com/ksc/hive-user-defined-functions.html > > In above link I am looking for functions but I get below one and I dont > understand following things: > > USING 'map_script'USING 'reduce_script' > > in following block: > > > FROM ( > FROM pv_users > MAP ( pv_users.userid, pv_users.date ) > USING 'map_script' > AS c1, c2, c3 > DISTRIBUTE BY c2 > SORT BY c2, c1) map_output > INSERT OVERWRITE TABLE pv_users_reduced > REDUCE ( map_output.c1, map_output.c2, map_output.c3 ) > USING 'reduce_script' > AS date, count; > > > Pls can anyone tell what is the use of scripts and how to write block > of queries in hive? > > > > > -- > Regards, > Bhavesh Shah > -- "...:::Aniket:::... Quetzalco@tl"
