Hi Kavya, > 3. Fixing a standby that lags a lot
Of the operational walls, this is the one I would size before committing rather than after, so I put together a small harness that turns it into a number: it loads indexed data, pauses replay to separate WAL generation from replay, then times pure replay from local WAL and reports MB/s with a 95% CI and a lag curve. About 15 minutes on a couple hundred MB, and it refuses assert-enabled builds so the timing is real: https://github.com/Manuelreyesbravo/standby-replay-ceiling The numbers are hardware-specific -- one laptop core replays around 190 MB/s here, CPU-bound. The point is to run it on a subset of your intended storage and CPU and get your own ceiling before building the full system, which matches Adrian's start-from-a-test-setup suggestion; whether one replay core keeps up then depends on how much WAL your write workload generates. It measures that wall, it does not move it. Happy to adjust it if your setup would test differently. Regards, Manu
