* Greg Smith <gsm...@gregsmith.com> [090109 18:39]: > I was hoping it might fall out of the other work being done in that area, > given how much that code is still being poked at right now. As Hannu > pointed out, from a conceptual level you just need to carry along the > same information that pg_current_xlog_location() returns to the archiver > on all the paths where a segment might end early.
I was(am) also hoping that somethig falls out of sync-rep that gives me better PITR backups (better than a small archive_timeout)... That hope is what made me abandon this patch after the initial feedback. > Rather than creating a whole new GUC, it might it be possible to turn > archive_mode into an enum setting: off, on, and cleaned as the modes > perhaps. That would avoid making a new setting, with the downside that a > bunch of critical code would look less clear than it does with a boolean. I'm content to wait and see what falls out of sync-rep stuff... ... for now ... > I understand the case you've made for why it doesn't matter, and for > almost every case you're right. The situation it may be vulnerable to is > where a burst of transactions come in just as the archive timeout expires > after minimal WAL activity. There I think you can end up with a bunch of > clients waiting behind an almost full zero fill operation, which pushes > up the worst-case latency. I've been able to measure the impact of the > similar case where zero-filling a brand new segment can impact things; > this would be much less like to happen because the timing would have to > line up just wrong, but I think it's still possible. Ya, and it's one of just many of the times PG hits these worst-latency spikes ;-) GEnerally, it's *very* good... and once in a while, when all the stars line up correctly, you get these spikes.... But even with these spikes, it's plenty fast enough for the stuff I've done... a. -- Aidan Van Dyk Create like a god, ai...@highrise.ca command like a king, http://www.highrise.ca/ work like a slave.
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