- Sequence of operation which will be performed to retrieve the query results
- Adding EXPLAIN keyword before the query and executing it, will show the Query Plan
- EXPLAIN framework prints the PLANNED STATEMENT in a user-friendly output
- EXPLAIN will not run the query, but will only show the plan.
- The below query plan indicates 2 operation
Step 1) Seq Scan --> The Table foo will be scanned on all the Segments
Step 2) Gather Motion --> All the scanned data in Step 1 will be Gathered at Master
EXPLAIN SELECT * FROM foo;
QUERY PLAN
-------------------------------------------------------------------------------
Gather Motion 2:1 (slice1; segments: 2) (cost=0.00..431.00 rows=2 width=12)
-> Seq Scan on foo (cost=0.00..431.00 rows=1 width=12)
What is a high level flow for a query?
