COALESECE in ADQL?
msdemlei at ari.uni-heidelberg.de
Thu Dec 9 14:52:57 CET 2021
Dear DAL folks,
In the context of my work on improving support for data discovery
(rather than service discovery) in pyVO (cf.
<https://github.com/msdemlei/pyvo/tree/add-discoverdata>), I've found
that writing queries that do that without SQL COALESCE is really hard
given the way RegTAP is written (using NULLs for missing access_urls,
standardIds, and such).
Since I consider data discovery (as per DDC
<https://ivoa.net/documents/discovercollections>) a mode of registry
use the role of which will grow significantly, I am fairly determined
to require COALESCE for RegTAP 1.2. That requirement is a lot easier
to state if ADQL itself already mentions COALESCE.
So, although I certainly do not want to further delay ADQL RFC, I've
put in a relatively compact PR,
https://github.com/ivoa-std/ADQL/pull/69 -- perhaps it could still
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