On 2015-10-22 17:47:01 -0500, Jim Nasby wrote: > On 10/22/15 5:11 PM, Robert Haas wrote: > >It's true that if the standby didn't have the master's FPIs, it could > >generate its own in some side location that behaves like a separate > >WAL stream or a double-write buffer. But that would be a heck of a > >lot of work to implement for an uncertain benefit. > > If the receiver didn't write the WAL before processing it then it can just > stick the page image into the WAL it's writing for itself. Probably not good > for syncrep, but I don't think you'd want this on for syncrep anyway.
To me this sounds like a recipe for disaster (i.e. complex bugs). WAL (and thus CRC checksums) differing between nodes. Ugh. > But yes, this is all very hand-wavy without any actual data on what > percentage of the WAL stream is FPIs. Looks like pageinspect doesn't work > for WAL... does anyone have a script/tool that breaks out what percentage of > a WAL file is FPIs? pg_xlogdump --stats -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers