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postgresqlhstore

How can I find out if a hstore is a subset of another hstore?

I have two hstore fields, that I want to compare, and I want to know if the one is a subset of the other?

So, let's say I have "foo"=>"bar","fnuggle"=>"snuggle","dwurp"=>"qwork" and "dwurp"=>"qwork", the result would be TRUE.

When I have "foo"=>"bar","fnuggle"=>"snuggle","dwurp"=>"qwork" and "dwurp"=>"dworp", the result should be FALSE.

Also, when I have "foo"=>"bar","fnuggle"=>"snuggle","dwurp"=>"qwork" and "dwurp"=>"qwork","flippin"=>"floppin", the result should be FALSE.

I worked through the hstore operators and other possibilities, but didn't find a good solution.

Solution

  • The answer turned out to be pretty simple. Consider big to be the superset and small the subset, this:

    slice(big, akeys(small)) = small

    returns TRUE when small is a subset.