has column ls_id been properly defined in ls_dr8.tractor_n?

Question

I recently ran a query using the online query tool (https://datalab.noao.edu/query.php) on the ls_dr8_tractor_s table requesting magnitudes and ls_id. The query ran and the ls_id seem to be unique but now I need to run this query on the northern catalog and based on the answer to this question (https://datalab.noao.edu/help/index.php?qa=636&qa_1=are-there-northern-dec-33-deg-entries-in-ls_dr8-forced) I see that:

a) ls_id is not to be trusted from the online query (not supported by ADQL)?  This isnt a big deal as I can run in a notebook but what then are the values in the ls_id column that I downloaded?

b) if run through a notebook are the ls_ids properly defined in the ls_dr8.tractor_n yet? I really just want to check uniqueness among matches to my objects.

Answer 1

Thank you for your question!

The ls_id in ls_dr8.tractor_n has recently been updated to the correct value and can be trusted online and through a notebook.  Before, it had the incorrect release encoded in it, making it likely to not be unique against tractor_s values.  i.e. it had 8000 for the release and not 8001. 

Here's an example of how it encodes the release, brickid, and objid now.

select ls_id, ((release::bigint<<40)::bigint|((BRICKID::bigint<<16)::bigint|(OBJID::bigint))) from ls_dr8.tractor_n limit 10;
      ls_id       |     ?column?     
------------------+------------------
 8797229300909075 | 8797229300909075
 8797229300909568 | 8797229300909568
 8797229300911473 | 8797229300911473
 8797229368738762 | 8797229368738762
 8797229300778048 | 8797229300778048
 8797229300782092 | 8797229300782092
 8797229300847940 | 8797229300847940
 8797229368672404 | 8797229368672404
 8797229368675255 | 8797229368675255
 8797229368740305 | 8797229368740305

HTH,

Adam