Hive Tutorial 24 : MR vs Tez execution engines in Hive

There are two execution engines available  to execute hive queries:

 1. Mr
2. Apache Tez

 set hive.execution.engine=mr
set hive.execution.engine=tez

 1. Mr:

          If we set execution engine as mr & executed the query, it will trigger map jobs first & store the result in local disks & the second job have to pick input from the local disk.Because of this the read/write operations show impact on its speed.
2. Apache Tez:

         If we set execution engine as Tez & executed the query, it uses DAG's i.e.., instead of storing into local disk, it uses in-memory .Hence the read/write operations will be done more faster when compare to Mr. Tez internally triggers Vectorization which helps to increase its process speed.

Observe the two images , the time taken for execution of the query using Tez engine is less than time taken by Mr engine.



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