How do i store hash indices on my database
There are several considerations:

Consistency: if you store everything in the database, consistency between database entries and the hash are automatically guaranteed by the transaction system. That simplifies architecture and development.

Read/Write Performance: reading bigger data from the database performs much worse than reading files from the file system.

Backup/Maintenance: large databases are more difficult to back up than large file systems.

Search performance: unless you build special GiST index support for operators on these hashes (which requires C programming and dealing with the guts of PostgreSQL), you won't be able to efficiently search for the hashes in the database.