2015-06-28 8:59 GMT+02:00 Fabien COELHO <coe...@cri.ensmp.fr>: > > \if_ver_eq 9.2 >>>> >>> >>> What do you thinking about it? >>> >>> Couldn't this kind of thing be done directly with PL/pgSQL? >>> >> >> you can use PL/pgSQL - but there are some limits >> >> * maintenance large plpgsql functions >> > > I agree with large but that would not necessarily mean complex. Also, some > functions could be in SQL, and just the logic with PL/pgSQL. > > * the plpgsql functions or anonymous functions create a transaction >> borders >> - what should not be wanted >> > > Hmmm... If something fails when installing an extension, a transaction > border is probably a good thing? Also, the interaction of \if with possible > BEGIN/COMMIT can lead to strange states. > > * I cannot to use psql variables simply in plpgsql code (plpgsql has not >> any macro language) >> > > You can call a function with a variable as an argument: > > \set foo 1234 > SELECT some_function(:foo); > > - so some patterns are implemented in plpgsql less readable >> > > Which pattern? >
you can use parameters for functions, but you cannot it for DO statement (simply). > > for example, if you can create a script that create some plpgsql function >> for specified PostgreSQL version, then using PLpgSQL for this purpose is >> suboptimal due less readability and maintainability >> > > I'm not that sure about the qualitative assessment, "DO" looks pretty neat > to me. > I can do with DO almost all work, but the result is not readable - I have to play with session variables, I have to play with more levels of custom string separator than is necessary Moreover this is to be balanced with creating a scope/block/nesting system > in psql which is currently alien to it and would bring its own pitfalls: > psql is really intrinsically line/statement oriented, that would not be the > case with what you're proposing as this logic would be deeply changed, and > people would get stuck within a non-closed \if, this would interact with \i > in possibly strange ways, and so on (say you include a file with a non > closed \if, and then everything you type seems to be ignored, or a BEGIN is > done in an if but the COMMIT was in another which was not activated because > the conditions where not consistent...). > > Basically, it looks like a potential Pandora box which is best left with > its lid on. > I don't propose full psql scripting - my proposal is much more enhancing the current psql macro possibilities. the implementation of \if_version_gt is pretty simple - needs few lines of new code > > -- > Fabien. >
