Re: Konstantin Knizhnik 2017-09-13 <2393c4b3-2ec4-dc68-4ea9-670597b56...@postgrespro.ru> > > > On 13.09.2017 10:51, Christoph Berg wrote: > > Re: Konstantin Knizhnik 2017-09-01 > > <f530ede0-1bf6-879c-c362-34325514f...@postgrespro.ru> > > > + Functional index is based on on projection function: function > > > which extract subset of its argument. > > > + In mathematic such functions are called non-injective. For > > > injective function if any attribute used in the indexed > > > + expression is changed, then value of index expression is also > > > changed. > > This is Just Wrong. I still think what you are doing here doesn't have > > anything to do with the function being injective or not. > > Sorry, can you please explain what is wrong?
I don't get why you are reasoning about "projection" -> "non-injective" -> "injective". Can't you try to explain what this functionality is about without abusing math terms that just mean something else in the rest of the world? Christoph -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
