Obscore-1_1-Next < IVOA

IVOA Web>IvoaDataModel>Obscore-1_1-Next (2024-04-15, MarkusDemleitner) (raw view)

This page collects proposals for modifications to ObsCore 1.1, leading
up to 1.2

---+ Proposed new Features

---++ Define a way to discover s_region usability

A major pain when doing "blind" obscore queries is that it would be nice
to query against s_region (because it is so much more flexible and
reliable than s_ra, s_dec, and s_fov), but support for s_region is not
universal.

Probably the easiest way to fix this would be to say "if you give s_ra
and s_dec, you MUST give s_region".  That would be my preferred
solution, actually.

Alternatively, there should be a way for data providers to say "you will
not get extra false negatives if you use s_region over s_ra and s_dec on
this table".  Ideally, this would not require Registry interaction; and
actually, the Registry does not have an out-of-the-box mechanism for
something like this either.  We would have to define an Obscore registry
extension for such a flag, and that seems overkill to me at this point.

I wonder if we should'nt just have a hack and say "if your s_region
column is fine, add the literal string 'safe-for-queries' to
s_region's description".  Yes, this may seem to radiate a bit of bad
karma, but it works nicely with both TAP_SCHEMA and VOSI, which is nice
and seems hard to attain with just about anything else.

Another alternative that has this property would be to change the
s_region's UCD or utype for query-safe (or non-query-safe?) s_region
columns... hm.


---+ Proposed modifications

---++ Improve Sample Queries

The example queries in the appendix should not show people
split-coordinate spatial constraints (s_dec&lt;20 and friends) and rather
use proper geometry constraints (circles or polygons).  Coordinate
queries are often not covered by indexes and are rarely a good idea
physically.

Also, it would be good if we could include at least one or two examples
which show how to just retrieve a subset of columns; "select *" may be
appropriate for certain use cases, but just pulling the data one needs
for a certain use case is better use of resources.  This may in general
not be dramatic in your average obscore query, but when people to
statistics on millions of matches, it does matter.

-- MarkusDemleitner 2023-01-16

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Topic revision: r2 - 2024-04-15 - MarkusDemleitner

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