Hi, On 2024-04-08 09:36:59 +1200, Thomas Munro wrote: > I've been on the fence about that flag for sequential scan... Some > days I want to consider changing to READ_STREAM_DEFAULT and relying on > our "anti-heuristics" to suppress advice, which would work out the > same in most cases but might occasionally win big.
Agreed, it's pretty easy to end up with a fairly "fragmented" set of a relation's buffers in s_b. OTOH, there might not be any need for the heuristic if we actually trigger reads asynchronously. > BTW looking at the branching in read-stream user patches that have an > initialisation step like yours, I wonder if it might every make sense > to be able to change the callback on the fly from inside the callback, > so that you finish up with a branchless one doing most of the work. I > have no idea if it's worth it... I was wondering about that too, I dislike those branches. But instead of changing the callback, it seems like a better design would be to have another dedicated callback for that? There already is a dedicated branch for the "just starting up" path in read_stream_next_buffer(), so it'd be pretty much free to call another callback there. Greetings, Andres Freund
