Hacker News Reader

HNHacker News

Top New Best Ask Show Jobs

Comment by SEJeff | Hacker News Reader

Parent Full thread

SEJeff·

Postgres supports JSONB natively. It literally speaks mongo line protocol and you can shove unstructured json into it.

It has supported this since 9.4: https://www.postgresql.org/docs/current/datatype-json.html

View on HN

I don't necessarily agree with the above justifications, but in my experience this is basically why teams pick Mongo.

It's easier to get started with.

It’s hard to disagree with you on that part. PG is definitely not free to get starts with and requires a bit of setup (hello pg_hba.conf).

Now there's a truth about MongoDB, it's easy to get started with.

But why is that the top priority?

Because some devs and teams prioritise “get to prod” above literally all else.

Maintainability? Secondary. Security? Secondary. Data-integrity/correctness? Secondary.

Yes but updating nested fields is last write wins, and with mongo you could update two fields separately and have the writes succeed, it's not equivalent.

Can you provide an example or documentation please?

When you write to a postgres jsonb field it updates the entire JSONB content, because that's how postgres's engine works. Mongo allows you to $set two fields on the same document at the same time, for example, and have both writes win, which is very useful and removes distributed locks etc. This is just like updating specific table columns on postgres, but postgres doesn't allow that within columns, you'd have to lock the row for updating to do this safely which is a PITA.

Reply on news.ycombinator.com