How to find indexes on a table in postgres

If you are logged in as a user whose search_path includes a schema the user has USAGE privilege on, use:

SELECT * 
FROM pg_indexes 
WHERE schemaname = current_schema();

For indexes on a specific table, in a specific schema, log onto the correct database as a privileged user:

[postgres@server1 ~]$ psql db01
db01=# \conninfo
You are connected to database "db01" as user "postgres" via socket in "/run/postgresql" at port "5432".

Execute the following SQL:

SELECT
    tablename,
    indexname,
    indexdef
FROM
    pg_indexes
WHERE
    schemaname = 'myuser'
    and tablename='mytable'
ORDER BY
    tablename,
    indexname;

tablename	indexname	indexdef
mytable	idx1	CREATE INDEX idx1 ON myschema.mytableUSING btree (col1, col2)
mytable	idx2	CREATE INDEX idx2 ON myschema.mytable USING btree (col3)

Or use the psql command \d mytable, which lists the indexes after the description of the table columns

\d mytable

 
Indexes:
    "pk_mytable" PRIMARY KEY, btree (col1)
    "idx1" btree (col1, col2)
    "idx2" btree (col3)
    "idx3" btree (col3, col4)