Hi, I've tested patch provided by Kyotaro and do confirm it fixes the issue. Any chance it will be merged to one of the next minor releases?
Thank you very much! сб, 1 февр. 2020 г. в 08:31, David Steele <da...@pgmasters.net>: > On 1/28/20 8:02 PM, Kyotaro Horiguchi wrote: > > At Tue, 28 Jan 2020 19:13:32 +0300, Pavel Suderevsky > >> Regading influence: issue is not about the large amount of WALs to > apply > >> but in searching for the non-existing WALs on the remote storage, > each such > >> search can take 5-10 seconds while obtaining existing WAL takes > >> milliseconds. > > > > Wow. I didn't know of a file system that takes that much seconds to > > trying non-existent files. Although I still think this is not a bug, > > but avoiding that actually leads to a big win on such systems. > > I have not tested this case but I can imagine it would be slow in > practice. It's axiomatic that is hard to prove a negative. With > multi-region replication it might well take some time to be sure that > the file *really* doesn't exist and hasn't just been lost in a single > region. > > > After a thought, I think it's safe and effectively doable to let > > XLogFileReadAnyTLI() refrain from trying WAL segments of too-high > > TLIs. Some garbage archive files out of the range of a timeline might > > be seen, for example, after reusing archive directory without clearing > > files. However, fetching such garbages just to fail doesn't > > contribute durability or reliablity at all, I think. > > The patch seems sane, the trick will be testing it. > > Pavel, do you have an environment where you can ensure this is a > performance benefit? > > Regards, > -- > -David > da...@pgmasters.net >
