Andres Freund <and...@anarazel.de> writes: > On 2016-04-16 16:44:52 -0400, Noah Misch wrote: >> That is more controversial than the potential ~2% regression for >> old_snapshot_threshold=-1. Alvaro[2] and Robert[3] are okay releasing >> that way, and Andres[4] is not.
> FWIW, I could be kinda convinced that it's temporarily ok, if there'd be > a clear proposal on the table how to solve the scalability issue around > MaintainOldSnapshotTimeMapping(). Postponing the optimization around > something as trivial as a spinlock around reading an LSN is one thing, > postponing something we don't know the solution to is anohter. The message Noah cited mentions only a 4% regression, but this one seems far worse: http://www.postgresql.org/message-id/20160413200148.bawmwjdmggbll...@alap3.anarazel.de That's more than a 5X penalty, which seems like it would make the feature unusable; unless there is an argument that that's an extreme case that wouldn't be representative of most real-world usage. Which there may well be; I've not been following this thread carefully. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
