On 09/17/2014 08:27 AM, Craig Ringer wrote:
Hi all
Attached is a patch to switch 9.5 over to using the
GetSystemTimeAsFileTime call instead of separate GetSystemTime and
SystemTimeToFileTime calls.
This patch the first step in improving PostgreSQL's support for Windows
high(er) resolution time.
In addition to requiring one less call into the platform libraries, this
change permits capture of timestamps at up to 100ns precision, instead
of the current 1ms limit. Unfortunately due to platform timer resolution
limitations it will in practice only report with 1ms resolution and
0.1ms precision - or sometimes even as much as 15ms resolution. (If you
want to know more, see the README for
https://github.com/2ndQuadrant/pg_sysdatetime).
On Windows 2012 and Windows 8 I'd like to use the new
GetSystemTimePreciseAsFileTime call instead. As this requires some extra
hoop-jumping to safely and efficiently use it without breaking support
for older platforms I suggest that we start with just switching over to
GetSystemTimeAsFileTime, which has been supported since Windows 2000.
Then more precise time capture can be added in a later patch.
That will presumably breaK XP. I know XP has been declared at EOL, but
there are still a heck of a lot of such systems out there, especially in
places like ATMs, but I saw it in use recently at a US surgical facility
(which is slightly scary, although this wasn't for life-sustaining
functionality). My XP system is still actually getting some security
updates sent from Microsoft.
I'm fine with doing this - frogmouth and currawong would retire on the
buildfarm.
Just wanted to be up front about it.
cheers
andrew
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