I'm discussing internals of a database system with someone and I'm struggling to figure out how do I talk about my past thought on the subject.
If I was just expressing my thoughts I would say "It is the visibility map that controls whether we do a heap fetch, and the map bits are set only by vacuum".
However, I need to express my past thoughts about it, which might be incorrect. My gut feeling suggests to say "I thought it was the visibility map that controls/controlled whether we do a heap fetch, and its bits were set only by vacuum". But I'm not sure about controls vs controlled and I feel like I need a general rule for this kind of situations.
Upd: regarding whether I don't think this any more: originally my sentence was something like "I thought ..., was I wrong?" or "I thought ..., but now I'm less sure."