Hello. At Thu, 14 Mar 2019 09:42:44 +0000, "Tsunakawa, Takayuki" <tsunakawa.ta...@jp.fujitsu.com> wrote in <0A3221C70F24FB45833433255569204D1FBC7626@G01JPEXMBYT05> > From: mikalaike...@ibagroup.eu [mailto:mikalaike...@ibagroup.eu] > > > For example, OS issues such as abnormally (buggy) slow process scheduling > > or paging/swapping that prevent control from being passed to postgres. Or, > > abnormally long waits on lwlocks in postgres. statement_timeout doesn't > > take effect while waiting on a lwlock. I have experienced both. And, any > > other issues in the server that we haven't experienced and not predictable. > > > > For me all mentioned by Takayuki Tsunakawa problems looks like a lack of > > design of end-user application or configuration of DB server. It is not > > a problem of PostgreSQL. > > Certainly, my cases could be avoided by the OS and database > configuration. But we cannot say all such problems can be > avoided by configuration in advance. The point is to provide a > method to get ready for any situation.
Right. We can't perfectly predict in advance what happens on a server and server cannot perfectly surmise in advance what every client wants. Clients can avoid something by using something that is not fully understood, that leads to another unpredictable trouble. This is the reason how a feature works should be understandable for users. I saw many cases where an HA cluster fails over for mysterious reasons for users, who are considered to understood them. (That happens more frequently on virtual machines.) If the application should return a response in, say, 10 seconds, the application should do that by itself. # I hope it is comprehensible.. regards. -- Kyotaro Horiguchi NTT Open Source Software Center
