On 2017-12-20 17:13:31 -0200, neto brpr wrote: > Just to explain it better. The idea of ​​differentiating read and write > parameters (sequential and random) is exactly so that the access plans can > be better chosen by the optimizer. But for this, the Hash join, merge join, > sorting and other algorithms should also be changed to consider these new > parameters.
I'm doubtful that there's that much benefit. Mergejoin doesn't write, hashjoins commonly don't write , and usually if so there's not that many alternatives to batched hashjoins. Similar-ish with sorts, although sometimes that can instead be done using ordered index scans. What are the cases you forsee where costing reads/writes differently will lead to better plans? Greetings, Andres Freund
