Re: Konstantin Knizhnik 2017-05-30 <f97118e3-821c-10a8-85ec-0af3f1dfd...@postgrespro.ru> > > > On 29.05.2017 20:21, Christoph Berg wrote: > > > > I think the term you were looking for is "projection". > > > > https://en.wikipedia.org/wiki/Projection_(set_theory) > > I have already renamed parameter from "surjective" to "injective". > But I am ok to do do one more renaming to "projection" if it will be > considered as better alternative. > From my point of view, "projection" seems to be clearer for people without > mathematical background, > but IMHO this term is overloaded in DBMS context.
With mathematical background, I don't see how your indexes would exploit surjective or injective properties of the function used. What you are using is that ->> projects a json value to one of its components, i.e. the projection/function result does not depend on the other attributes contained. > The irony is that in Wikipedia "projection" is explained using > "surjection" term:) For the equivalence classes part, which isn't really connected to your application. Christoph -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
