[killedbydeath]

If you need to store arbitrary JSON fields in the database and index them, then you indeed are better of with some NoSQL database. But I strongly disagree with the statement that all new startups deal with that kind of data organization. Many problems have good structure and can benefit from imposing structure (schema) upfront. In which case any JSON you get will parse in the application, map it to your data organization and store in a clean strict relational format, with all indexable fields extracted to separate columns. I do not store my logs in Postgres, but I do store my billing transactions in Postgres. There are many different types of data with different tradeoffs involved. For most, Postgres is a great choice.