Re: what is flushed?

Martijn van Oosterhout <kleptog(at)svana(dot)org> writes:

> WAL has been a feature of Postgresql for years now... So yes, it's
> somewhat out of date...

Actually it kind of depends what it means. I think WAL records were always
written with fsync (or fdatasync/O_SYNC/O_DSYNC).

However right up until 7.4 checkpointing was done with sync(2). This means
that other unrelated i/o could cause unneeded delay at checkpoint time. This
would have been an especially big hit for shared servers running other
write-intensive services such as, say, mail.

The impetus to finally fix this came from the Windows port since Windows
simply didn't have sync(2). Afaik 8.0 won't have to issue a sync(2) call ever.

--
greg