Databases and shiny

Hello! I have a quick question about databases and shiny and when it makes sense to use them. Theres a really good discussion about databases in general here: Disagree with Hadley's comment about databases

Just like OP, I was also shocked about the advice on when to use and when not to use a database. However, I'm not an expert on this stuff.

Anyways, consider the following scenario:

  • Shiny app
  • Multiple users
  • Data ranging from 20,000 to ~2,000,000 rows by 90ish columns, depending on the table
  • Data fits in memory

I chose to go with a database because my feeling (without any evidence) was that if multiple users are accessing at once (multiple sessions with future/promises), I would be loading multiple flat files at once which would eventually not fit into memory. Is this hunch of mine correct? Is it a good idea to use databases in my scenario?