On Fri, Jan 26, 2007 at 09:55:39AM -0500, Tom Lane wrote: > Magnus Hagander <magnus@xxxxxxxxxxxx> writes: > > Apparantly there is a bug lurking somewhere in pgwin32_select(). Because > > if I put a #undef select right before the select in pgstat.c, the > > regression tests pass. > > I guess the bug is shown because with row level stats we simply have > > more data to process. And it appears only to happen on UDP sockets from > > what I can tell. > > Hmm ... if this theory is correct, then statistics collection has > never worked at all on Windows, at least not under more than the most > marginal load; and hence neither has autovacuum. We have had lots of reports of issues with the stats collector on Windows. Some were definitly fixed by the patch by O&T, but I don't think all. The thing is, since it didn't give any error messages at all, most users wouldn't notice. Other than their tables getting bloated, in which case they would do a manual vacuum and conlcude autovacuum wasn't good enough. Or something. > Does that conclusion agree with reality? You'd think we'd have heard > a whole lot of complaints about it, not just Jeremy's; and I don't > remember it being a sore point. (But then again I just woke up.) > What seems somewhat more likely is that we broke pgwin32_select > recently, in which case we oughta find out why. Or else remove it > entirely (does your patch make that possible?). AFAIK, it only affects UDP connections, and this patch takes pgwin32_select out of the loop for all UDP stuff. But if we get this in, pgwin32_select is only used in the postmaster accept-new-connections loop (from what I can tell by a quick look), so I'd definitly want to rewrite that one as well to use a better way than select-emulation. Then it could go away completely. > Keep in mind also that we have seen the stats-test failure on > non-Windows machines, so we still need to explain that ... Yeah. But it *could* be two different stats issues lurking. Perhaps the issue we've seen on non-windows can be fixed by the settings Alvaro had me try (increasing autovacuum_vacuum_cost_delay or the delay in the regression test). //Magnus
