Could you tell me how to check what indexes are created for some table in postgresql ?
The view pg_indexes provides access to useful information about each index in the database, e.g.:
select *
from pg_indexes
where tablename = 'test'
The pg_index system view contains more detailed (internal) parameters, in particular, whether the index is a primary key or whether it is unique. Example:
select
c.relnamespace::regnamespace as schema_name,
c.relname as table_name,
i.indexrelid::regclass as index_name,
i.indisprimary as is_pk,
i.indisunique as is_unique
from pg_index i
join pg_class c on c.oid = i.indrelid
where c.relname = 'test'
See examples in db<>fiddle.