pg_repack: WARNING: relation must have a primary key or not-null unique keys

Hello everyone!

eugene(at)dignus:/var/www/html/health$ psql xbox
Timing is on.
psql (12.3 (Ubuntu 12.3-1.pgdg20.04+1))
Type "help" for help.

xbox=> \d herostat
Table "public.herostat"
Column | Type | Collation | Nullable | Default
----------+------------------+-----------+----------+---------
xuid | bigint | | not null |
titleid | bigint | | not null |
value | text | | |
valfloat | double precision | | |
heroid | integer | | not null |
Indexes:
"herostat_pkey" PRIMARY KEY, btree (xuid, titleid, heroid) INCLUDE
(valfloat)
"herostat_heroid_idx" btree (heroid)
"herostat_titleid_idx" btree (titleid)
Triggers:
herostat_min_update BEFORE UPDATE ON herostat FOR EACH ROW EXECUTE
FUNCTION suppress_redundant_updates_trigger()

xbox=> \q
eugene(at)dignus:/var/www/html/health$ sudo -u postgres pg_repack -t herostat
-N -d xbox
INFO: Dry run enabled, not executing repack
WARNING: relation "public.herostat" must have a primary key or not-null
unique keys
eugene(at)dignus:/var/www/html/health$ pg_repack --version
pg_repack 1.4.5
eugene(at)dignus:/var/www/html/health$

What is wrong and what I can do to fix it?

--
Evgeny Pazhitnov