Currently in our production environment we use hive on tez instead of mapreduce engine ,so i wanted to ask will all the hive optimization for joins will be relevant for tez as well? for example in multitable table it was mentioned that if join key is same then it will use single map reduce job,but when i checked on HQL in our environment where we were joining one table left outer with many table on same key I didnt see 1 reducer,infact there were 17 reducers running .so is it because hive on tez will be different than hive on mr?
Hive version : 1.2 Hadoop :2.7 Below is the documentation where it mentions using 1 reducer only https://cwiki.apache.org/confluence/display/Hive/LanguageManual+Joins
