On Sun, Mar 04, 2018 at 03:31:31PM -0500, Tom Lane wrote: > Then, seeing that the factory defaults are ReservedBackends = 3 and > max_wal_senders = 10, something's got to give; there's no way that > max_connections = 10 can work with those. But what I would argue is that > of those three choices, the least defensible one is max_wal_senders = 10. > Where did that come from? What fraction of real-world installations will > need that? We don't choose defaults that overprovision small > installations by 5X or 10X anywhere else, so why here?
Those numbers are coming from f6d6d29, which points to this thread at its root: https://www.postgresql.org/message-id/CABUevEwfV7zDutescm2PHGvsJdYA0RWHFMTRGhwrJPGgSbzZDQ%40mail.gmail.com The number of max_wal_senders came out as a consensus because those are cheap to enable, now the number came out by itself. I am not seeing on the thread any specific reason behind. > My proposal is to default max_wal_senders to perhaps 3, and leave > initdb's logic alone. I agree with you here. That was actually my first counter proposal on the matter, which is also conservative: https://www.postgresql.org/message-id/CAB7nPqSFzsO6bEknEQ8yidwXOOUUeCc05NKsPQFhMWBFPv3Smg%40mail.gmail.com -- Michael
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