On Sun, Feb 21, 2016 at 3:37 AM, Andres Freund <andres@anarazel.de> wrote:
>> The documentation seems to use "flush" but the code talks about "writeback"
>> or "flush", depending. I think one vocabulary, whichever it is, should be
>> chosen and everything should stick to it, otherwise everything look kind of
>> fuzzy and raises doubt for the reader (is it the same thing? is it something
>> else?). I initially used "flush", but it seems a bad idea because it has
>> nothing to do with the flush function, so I'm fine with writeback or anything
>> else, I just think that *one* word should be chosen and used everywhere.
>
> Hm.
I think there might be a semantic distinction between these two terms.
Doesn't writeback mean writing pages to disk, and flushing mean making
sure that they are durably on disk? So for example when the Linux
kernel thinks there is too much dirty data, it initiates writeback,
not a flush; on the other hand, at transaction commit, we initiate a
flush, not writeback.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company