Re: Page-at-a-time Locking Considerations

Tom Lane wrote:
> Zdenek Kotala <Zdenek.Kotala@Sun.COM> writes:
>> Tom Lane wrote:
>>> If you only got 2% out of it, it's not even worth thinking about how to
>>> fix the serious bugs that approach would create (primarily, lack of
>>> control over when pages can get flushed to disk).
> 
>> You can flush a pages by msync() function which writes dirty pages on 
>> disk. I don't see any other problem.
> 
> Then you need to learn more.  The side of the problem that is hard to
> fix is that sometimes we need to prevent pages from being flushed to
> disk until some other data (typically WAL entries) has reached disk.
> With mmap'd data we have no control over early writes.

I see. Thanks for explanation.
    Zdenek