What indexes were used in the query?

Question

PostgreSQL

Greetings!
Where and how to see which indexes were used in postgresql when querying?
I did explain and explain analyze, but I can’t understand where there is about indexes

Answer 1

If you don't see any indexes, then the scheduler has decided not to use the index. Here is the code from posgresql developer habr

postgres=# explain (costs off) select * from t where a = 1;
          QUERY PLAN          
-------------------------------
 Index Scan using t_a_idx on t
   Index Cond: (a = 1)
(2 rows)

где строчка " Index Scan using t_a_idx on t" означает использование индекса.

And proceeding from the explain'a laid out by you it is visible that the scheduler preferred Seq scan (consecutive scanning). And, in your request, the index is not needed at all. You don't even have a WHERE clause.