On 10/6/16, Tom Lane <t...@sss.pgh.pa.us> wrote: > Serge Rielau <se...@rielau.com> writes: >>> On Oct 6, 2016, at 5:25 AM, Vitaly Burovoy <vitaly.buro...@gmail.com> >>> wrote: >>>> Which makes me think we should call this missing_value or absent_value
Be honest Simon Rigg's wrote that words. >>>> so its clear that it is not a "default" it is the value we use for >>>> rows that do not have any value stored for them. > >> I like Tom’s “creation default”. Another one could be “initial default”. >> But that, too, can be misread. > > Something based on missing_value/absent_value could work for me too. > > If we name it something involving "default", that definitely increases > the possibility for confusion with the regular user-settable default. > > Also worth thinking about here is that the regular default expression > affects what will be put into future inserted rows, whereas this thing > affects the interpretation of past rows. So it's really quite a different > animal. That's kind of leading me away from calling it creation_default. > > BTW, it also occurs to me that there are going to be good implementation > reasons for restricting it to be a hard constant, not any sort of > expression. We are likely to need to be able to insert the value in > low-level code where general expression evaluation is impractical. Yes, I mentioned that it should be evaluated and stored as a value because user functions can be changed (besides the speed reason), that's why I like the "value" in its name. The "default" is usually identified with expressions, not values (which are particular cases of expressions). Serge mentioned the phrase "pre-existing rows", which makes me think about something like "pre_existing_value".... -- Best regards, Vitaly Burovoy -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
