Outsource review of PostgreSQL and Django servers?

Question

PostgreSQL

Hello.
There was a performance issue with an existing solution.
On board, a large PostgersSQL (more than a billion records) and a WebServer written in Django (10 - 20 thousand lines of code) are satisfied.
In the company, unfortunately, there are no people who know SQL well (how to build queries correctly, how to analyze performance).
Accordingly, we would like to involve a specialist (s) to review the existing solution.
We would have gained experience and guidance on refactoring and performance gains, and they would have been properly rewarded.
I don’t want to let anyone get into my code, I still would like to have a really SPECIALIST who understands what’s what, who can explain why this is so, and how to do it right and how he found this bottleneck.
It is unlikely that I just came up with a new line of business, for sure such services already exist, but:
1. I could not correctly form a Google query.
2. I would like to know if someone used something similar and what was the result.
3. How much will it cost and how long will it take.
Thanks

Answer 1

The guys from www.revsys.com/ immediately came to mind - they specialize in PostgreSQL and some Django authors work there.