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Archive Plan (2013)

https://library.nrao.edu/public/memos/gbt/GBT_286.pdf

Plan Going Forward

  1. Develop mapping from gbt_metadata schema or gbt fits files to the new archive schema
  2. Design an interface format for communicating the mapping
  3. GBT software to product the interface document
  4. NRAO software to update new archive schema from the interface document
  5. Design trigger to initiate transfer (or some push/pull mechanism)
  6. Policy issues?
    1. Long-term usage of GBT metadata database

Preliminary Notes

The required search fields for the GBT in the AAT are specified in the SRDP requirements document.

At this point, I’m pretty comfortable that I could write up a list of tables/columns in the new archive
schema that would need to be populated and where those currently exist (table/column) in gbt_metadata.
I think there are still a couple of things I’m not clear about, but it might be better to get that started and then
see what’s missing.

To start, the following tables are the most important:

Science Metadata

projects
authors
execution_blocks
scans
subscans
data_descriptions (frequency, bandwidth, polarization)

some additional tables for lookup (polarization)

NGAS index tables

execution_blocks
filegroups
files

The Science Metadata an NGAS index tables form a parallel structure. So if I’m a user, most of my interaction
will be with the Science Metadata tables (show me all projects observing source ‘xxxxx’. Show me all projects
using GUPPI and Vegas Pulsar (probably Dave Freyer only :)

In order to retrieve the data, the system needs to translate the results of that query into an NGAS address for
data retrieval. You could start at the execution_blocks (the very top) which is why I included that on the NGAS side
as well. However, we also provide a link to the files table from either scan or subscan, depending on the appropriate
observing criteria (1fits file = 1 scan or 1 fits file = 1 subscan, etc.).

Open Issues


  1. What are the restrictions on retrieving data in SDFITS format and what are the advantages of using this over a list of fits files?
  2. How is a SDMFITS format file generated and is this working correctly
  3.  What is currently archived in NGAS - SDFITS files, or individual fits files


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