What is stored in postgres database?

I was trying a indico 2.7.5 instance for a while, and recently considering upgrading postgres9.6 to postgres13. But when I look into postgres/indico database, I only find one table and one recode:

indico-# \d
             List of relations
 Schema |      Name       | Type  | Owner  
 public | alembic_version | table | indico
(1 row)
indico=# \d alembic_version
                    Table "public.alembic_version"
   Column    |         Type          | Collation | Nullable | Default 
 version_num | character varying(32) |           | not null | 
    "alembic_version_pkc" PRIMARY KEY, btree (version_num)
indico=# select * from alembic_version ;
(1 row)

I’m new to database, so I’m not sure:

  1. It’s that right? My indico seems working fine. (added users, established events without error)
  2. If nothing wrong, where are those user data and events stored? What is stored with postgres and what should I backup before upgrading?

there are many other schemas in that database that contain all the data. (due to the large amount of tables we grouped them by logical modules using schemas)

Thank you sir, I’m not familiar with database. Found them now. And one more question: what dose redis do for indico? I entered it when setup, and it’s not more mentioned in guide.

it’s used for caching stuff, storing login sessions and for celery to communicate. so nothing valuable in there.

Thank you, kind sir!