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[McIDAS #SLI-227764]: NEXRCALL



Hi Kwan,

re: work needed for archive dataset access

> I do notice the extreme slow speed when accessing older data.  Given
> this situation, I try to capture the images real time for a particular
> feature of interest.  But this is not always possible.  So often
> times, I want to go back and check yesterday's images.  So I would
> think that if there are about 36 hours of images handy, that should
> pretty much cover my typical needs.  In less typical occasions, I may
> want to access data from a few days old to about a week old.
> 
> Thanks for the quick fix.  But, yes, the speed is extremely slow.

re:
> Because of the extremely slow access time, IMGREMAP was sometimes
> timed out!
> 
> IMGREMAP NEXRCALL/1KN0R-NAT SCRATCH/IMAGES2.2 DAY=2009128 TIM=11:3
> 11:6 PRO=PS 60 93 RES=1 LAT=38 93 SSI=1496 2660 SIZ=1496 2660
> select timed out
> IMGREMAP: Failed to open source directory
> IMGREMAP failed, RC=1

I just installed an update to SSEC's support for access to "archive"
datasets.  The original SSEC implementation supported access to
datasets stored by day with directory names of the form YYYYDDD
(year and Julian day).  Our approach to storing multiple days of
data was to organize images into daily directories with names of
the form YYYYMMDD (year, month and day), so I could not readily
take advantage of the work that SSEC had done.  I updated the code
to support both directory naming schemes and change the dataset
definitions for the NEXRCALL datasets.

I think you will now find that access to images from a particular
day is now _much_ faster.

The downsides to this approach are:

- the user is required to include the DAY= keyword on all IMG*
  commands

- one can not generate or display a list of files that a day
  boundary

Here are some examples of what works and what doesn't:

IMGLIST NEXRCALL/1KN0R-NAT          <- fails because DAY= is not specified
IMGLIST NEXRCALL/1KN0R-NAT DAY=129  <- works
IMGDISP NEXRCALL/1KN0R-NAT DAY=130 LAT=...  <- works

IMGLIST NEXRCALL/2KN1P-NAT          <- fails because DAY= is not specified
IMGLIST NEXRCALL/2KN1P-NAT DAY=129  <- works
IMGDISP NEXRCALL/2KN1P-NAT DAY=130 LAT=...  <- works

IMGLIST NEXRCALL/4KNTP-NAT          <- fails because DAY= is not specified
IMGLIST NEXRCALL/4KNTP-NAT DAY=129  <- works
IMGDISP NEXRCALL/4KNTP-NAT DAY=130 LAT=...  <- works

Cheers,

Tom
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Ticket Details
===================
Ticket ID: SLI-227764
Department: Support McIDAS
Priority: Normal
Status: Closed


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