When i am using cmd, grunt> explain student_relation; , It shows Logical,Physical and MR Plan.What is exact mean of these plans and how they are used.

mhdeshmukh22 — Sat, 12 Mar 2016 22:55:15 GMT

Re: When i am using cmd, grunt> explain student_relation; , It shows Logical,Physical and MR Plan.What is exact mean of these plans and how they are used.

aervits — Sat, 12 Mar 2016 23:05:08 GMT

Use the EXPLAIN operator to review the logical, physical, and map reduce execution plans that are used to compute the specified relationship.

If no script is given:

The logical plan shows a pipeline of operators to be executed to build the relation. Type checking and backend-independent optimizations (such as applying filters early on) also apply.
The physical plan shows how the logical operators are translated to backend-specific physical operators. Some backend optimizations also apply.
The mapreduce plan shows how the physical operators are grouped into map reduce jobs.

mhdeshmukh22 — Sat, 12 Mar 2016 23:22:47 GMT