Andres Freund <and...@anarazel.de> writes: > On 2022-11-21 16:17:56 -0500, Robert Haas wrote: >> But ... what if they're not? Could the index contain a large number of >> pages containing just 1 tuple each, or no tuples at all? If so, maybe >> we can read ten bazillion index pages trying to find each heap tuple >> and still end up in trouble.
> ISTM that if you have an index in such a poor condition that a single > value lookup reads thousands of pages inside the index, planner > estimates taking long is going to be the smallest of your worries... Yeah, that sort of situation is going to make any operation on the index slow, not only get_actual_variable_endpoint(). I think we should content ourselves with improving the demonstrated case, which is where we're forced to do a lot of heap fetches due to lots of not-all-visible tuples. Whether we can spend a lot of time scanning the index without ever finding a tuple at all seems hypothetical. Without more evidence of a real problem, I do not wish to inject warts as horrid as this one into the index AM API. regards, tom lane