Analysing Performance of DB Queries

How can you understand if your Database queries are actually being indexed or not and how efficiently they are searching?

PostgreSQL

Let's look at how we can analyze the queries in PostgreSQL:

explain analyze select id, name from employees where id = 12

MongoDB

In case of mongodb as well there is an explain after collection name which you can use to understand the query performance:

You can use the cursor.explain() method or the db.collection.explain() method to determine whether or not a query uses an index. On using explain in mongodb queries you can notice that in case of query which requires full search will be in COLLSCAN status.

Now in case of efficient searching with indexes, it will be in the stage: IXSCAN

References

Find Out if a Query uses an Index in MongoDBDatabase.Guide