SIA-2.0: query params for string values

[Patrick Dowler]

With the addition of query parameters for addtional fields from ObsCore, 
the SIA-2.0 query capability allows one to query several string-valued 
fields: collection, obs_publisher_did, facility_name, instrument_name, 
target_name, dataproduct_type. With that comes the usual question/desire 
to do more than just equality comparison. In the past, we have had 
lengthy discussions about wildcards (and the escape-mechanism you need 
to search for the wildcard char itself :-) with no useful conclusion 
ever reached.

Now, we have a proposal to define string-value comparisons such that:

FOO=abc

is satisfied if "abc" matches a substring of the stored value (foo 
contains "abc"). I haven't really thought this through, but there are 
cases where exact match is the  better behaviour (e.g. 
ID=<obs_publisher_did>) and others where substring matching is arguably 
better... but I'm not convinced and I'm not crazy about different params 
behaving differently depending on one sentence in the spec.


A second complete orthogonal issue that has come up before is case 
sensitivity. Should we define these comparisons to always be 
non-case-sensitive? There is the fact that ObsCore dataproduct_type has 
fixed lowercase values defined, so this doesn't make sense there, but we 
can word carefully for such "enumerated" values to not open it up to 
mixed or upper case there.


Q1 - equality match or substring match?

Q2 - case sensitive or non-case-sensitive?

-- 

Patrick Dowler
Canadian Astronomy Data Centre
National Research Council Canada
5071 West Saanich Road
Victoria, BC V9E 2E7

250-363-0044 (office) 250-363-0045 (fax)