On Wed, Aug 17, 2016 at 11:34 AM, Victor Wagner <vitus@wagner.pp.ru> wrote:
On Wed, 17 Aug 2016 10:58:09 +0300 Oskari Saarenmaa <os@ohmu.fi> wrote:
> > The attached patch replaces FileWrite and FileRead with FileWriteAt > and FileReadAt and removes most FileSeek calls. FileSeek is still > around so we can find the end of a file, but it's not used for > anything else.
It seems that configure test for availability of pread/pwrite functions and corresponding #define is needed.
I don't think that all platforms, supported by PostgreSQL support this API. Especially, I cannot find any mention of pread/pwrite in the Win32 except this thread on stackoverflow:
Yeah, Windows does not have those API calls, but it shouldn't be rocket science to write a wrapper for it. The standard windows APIs can do the same thing -- but they'll need access to the HANDLE for the file and not the posix file descriptor.
It also has things like ReadFileScatter() (https://msdn.microsoft.com/en-us/library/windows/desktop/aa365469(v=vs.85).aspx) which is not the same, but might also be interesting as a future improvement. That's clearly something different though, and out of scope for this one. But IIRC that functionality was actually added for the sake of SQLServer back in the days.
