These things sound like they'd be true of environments with dysfunctional or naive RDBMS practices. While it may not be true for inexperienced developers, an e

These things sound like they'd be true of environments with dysfunctional or naive RDBMS practices. While it may not be true for inexperienced developers, an experienced developer can assume proper index use (because it's part of their responsibility to ensure or implement) and has access to sufficient heuristics about how a query will perform. And when it should and shouldn't be assumed to be predictable. (Again, informed by experience.) If you only know the ORM layer, which is unfortunately becoming more common, of course you don't have the full picture and can't make proper decisions.