Big Data storage, for relative data storage I have 2 tables in MySQL DB.

account - Around million records and increasing


id
name


proposal - 5,000 records and increasing


id
name


I have some algorithm that runs and find fit between account and proposal I want save the matches in DB, that will be filled from some queue manager, etc. So I can fetch the proposals much faster.

So that table will look like

account_proposal


account_id
proposal_id


As I understand I need to save at most 1M X 5K records I think it will be too heavy for MySQL and I want to solve the problem for future, when I will have 30M Accounts and 0.5M proposals.

So my question is which db engine fits more for saving such data?
This is not a database question, this is a mathematical question.  Mathematicians love problems like that -- find the best match between these 30M things and those 500K things.  It's sort of like matching your picture against all images in Facebook.

The mathematicians will (you can hope) come up with a way of chopping the problem up into pieces and coming up with an approximate best fit in a few million operations instead of 15 trillion operations.  Once you find that algorithm, then database gurus can discuss how to best store and fetch the data involved.

You will need to give the math guys the details of the function for metric of "closeness".  Part of the answer will probably take advantage of those details.