Re: Instrument checkpoint sync calls

Robert Haas wrote:
> I'm wondering why md.c is converting the results from an exact value to a floating
> point, only to have xlog.c turn around and convert back to an integer.
>  I think it could just return milliseconds directly, or if you're
> worried about a checkpoint that takes more than 24 days to complete,
> seconds and microseconds.

md.c is printing the value as a float, so I converted early to a double 
and then percolated it upward from there.  More an artifact of how the 
code grew from its initial form than an intentional decision. I see your 
point that making elapsed, total_elapsed, ckpt_agg_sync_time, and 
ckpt_longest_sync all the same type of integer that 
INSTR_TIME_GET_MICROSEC returns would reduce the potential for rounding 
abberations.  I could do another rev of the patch tomorrow with that 
change if you'd prefer it that way.  I don't have a strong opinion about 
that implementation detail; given that xlog.c is printing a less 
fine-grained time anyway (seconds with 3 digits vs. msec with 3 digits) 
it seems unlikely to run into a real problem here.

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Greg Smith   2ndQuadrant US    greg@2ndQuadrant.com   Baltimore, MD
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