Execution plan in SAP HANA

Do you have a slow query in Hana?
Do you want to improve the performances of a query?

First step is to retrieve the execution plan:

 DELETE FROM explain_plan_table WHERE statement_name = 'marco test nr 1';  
 DELETE FROM explain_plan_table WHERE statement_name = 'marco test nr 1';  
 EXPLAIN PLAN SET STATEMENT_NAME = 'marco test nr 1' FOR  
 select * from dummy; --put here your query!!!  
   
   
   
 SELECT 
   table_size,   
   to_number(output_size, 10, 2) as output_size,   
   to_number(subtree_cost, 10, 2) cost,   
   operator_name,   
   operator_details,   
   table_name  
 FROM explain_plan_table  
 WHERE statement_name = 'marco test nr 1'  
 order by operator_id;    

The output of the last select will look like this in your SAP HANA STUDIO:

In order to read the execution plan, I believe that the most important column is the "Operator Name". 
This is the column telling you how the DBMS is approaching the problem. 
Here you will see if it is doing something stupid. 
The question is: what is the meaning of the content of this column? Here is the set of possible values: 

Operator Name	Description
ROW SEARCH	Starting position of row engine operators. OPERATOR_DETAILS lists projected columns.
LIMIT	Operator for limiting number of output rows
ORDER BY	Operator for sorting output rows
HAVING	Operator for filtering with predicates on top of grouping and aggregation
GROUP BY	Operator for grouping and aggregation
MERGE AGGREGATION	Operator for merging the results of multiple parallel grouping and aggregations
DISTINCT	Operator for duplicate elimination
FILTER	Operator for filtering with predicates
UNION ALL	Operator for producing union-all of input relations
MATERIALIZED UNION ALL	Operator for producing union-all of input relations with intermediate result materialization
BTREE INDEX JOIN	Operator for joining input relations through B-tree index searches. Join type suffix can be added. For example, B-tree index join for left outer join is shown as BTREE INDEX JOIN (LEFT OUTER). Join without join type suffix means inner join.
CPBTREE INDEX JOIN	Operator for joining input relations through CPB-tree index searches. Join type suffix can be added.
HASH JOIN	Operator for joining input relations through probing hash table built on the fly. Join type suffix can be added.
NESTED LOOP JOIN	Operator for joining input relations through nested looping. Join type suffix can be added.
MIXED INVERTED INDEX JOIN	Operator for joining an input relation of row store format with a column table without format conversion using an inverted index of the column table. Join type suffix can be added.
BTREE INDEX SEARCH	Table access through B-tree index search
CPBTREE INDEX SEARCH	Table access through CPB-tree index search
TABLE SCAN	Table access through scanning
AGGR TABLE	Operator for aggregating base table directly
MONITOR SEARCH	Monitoring view access through search
MONITOR SCAN	Monitoring view access through scanning

Source of information: 
https://help.sap.com/hana/html/sql_explain_plan.html