Re: Tracking last scan time

On Thu, Sep  1, 2022 at 09:46:59AM +0100, Dave Page wrote:
> On Wed, 31 Aug 2022 at 17:13, Bruce Momjian <bruce@momjian.us> wrote:
>     Wow.  I was just thinking you need second-level accuracy, which must be
>     cheap somewhere.
>
>
> Second-level accuracy would indeed be fine for this. Frankly, for my use case
> just the date would be enough, but I can imagine people wanting greater
> accuracy than that. 
>
> And yes, I was very surprised by the timing results I got as well. I guess it's
> a quirk of macOS - on a Linux box I get ~4s for gettimeofday() and ~1s for time
> ().

i think we lose 95% of our users if we require it to be enabled so let's
work to find a way it can be always enabled.

if (pgstat_track_scan_timestamps && lstats->t_counts.t_numscans)
{
    TimestampTz t = GetCurrentTransactionStopTimestamp();
    if (t > tabentry->lastscan)

        tabentry->lastscan = t;