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postgres=# SELECT pg_size_pretty( pg_database_size('hive') );
 pg_size_pretty
----------------
 181 GB
(1 row)

181 GB for hivemind. But beware, Hive doesn't store all the data of the blockchain.

Thanks for this, I see it's a Postgres db in the back then.

I am interested in only a subset of the data. Is it possible to filter posts where the parent id is empty (i.e. only get back posts, not comments)?

Going to read up a bit more.