Yes, I get that, but in this case that should only be about an order of
magnitude difference in access speed, since he is only reading 8 values
(hitting the disk 8 times instead of the 1 time it would take for a
variable that is not unlimited.)
But he is describing a much larger difference in performance...
On Thu, Jun 2, 2016 at 5:01 PM, Dave Allured - NOAA Affiliate <
dave.allured@xxxxxxxx> wrote:
> On Thu, Jun 2, 2016 at 2:41 PM, Ed Hartnett <edwardjameshartnett@xxxxxxxxx
> > wrote:
>
>> I don't think the fact that it is an unlimited dimension should make it
>> any slower, either in classic
>>
>
> <snip>
>
> Ed, I have experienced this slow down many times with Netcdf-3 classic.
> As I said earlier, if the format is classic, then a coordinate variable on
> the unlimited dimension is scattered throughout the file. This is
> confirmed in the Users' Guide. At the low level, many disk blocks must be
> read to get the complete coordinate array.
>
> --Dave
>
