Why the tradeoff exists
An index is another representation of your data. Reading through it may be faster, but inserting or updating records also means maintaining that representation. A wider index can cover more of a query while consuming more space.
The AnythingLLM tradeoff
Our local candidate accelerated the target quota query but used roughly 9% more database storage and slowed bulk inserts. All six tested million-row sequences that omitted the quota check regressed. Removing the benefiting query changed the decision.
Define the workload first
A chat system that frequently checks quotas is different from an import-heavy system or one where that check rarely runs. Compare the read/write mix, data volume, cache conditions, and user actions that your deployment actually has.
What responsible delivery looks like
Document where a change helps and where it hurts. Keep correctness checks around both reads and writes. Prefer a qualified recommendation with clear workload conditions over a universal performance claim that the evidence cannot support.