2016-11-29 8:44 GMT+01:00 Fabien COELHO <coe...@cri.ensmp.fr>: > > Hello, > > I think it's really time we seriously considered adding some flow >>> control logic, though. >>> >> >> Yeah, maybe. I'd be interested to see a fully worked out proposal >> for that. >> > > I agree that designing a fuller proposal before including individual parts > would be great and result in a more consistent result. > > In order to bootstrap the discussion, I suggest the following: > > - boolexpr is a simple "boolean" (t, non 0 int, non empty string.. as > proposed by Corey and Pavel) or !/not boolexp ; it could be extended if > necessary, but I would try to avoid that, as >
Now, the psql statements are designed do nothing in syntax error. I am not sure about be more strict in this case. I see strong advantages - but it can be little bit different than current behave. > > - actual more complex expressions could be left to the server through SQL > which simplifies the client a lot by avoiding an expression language > altogether > > - then having a conditional block is very versatile and can be adapted to > many use cases... maybe all > > - \quit CODE, or I would prefer \exit CODE, could be used to exit while > controlling the status > > It could look like (although I do not like gset in this context, but > anyway): > > SELECT ... AS has_foo_extension \gset > SELECT ... AS has_bla_extension \gset > \if :has_foo_extension > ... > \elif :has_bla_extension > ... > \else -- no foo nor bla extension > \echo please install foo or bla extension > \exit 1 > \fi -- extension > ... > SELECT ... AS has_xxx_feature \gset > \if ! :has_xxx_feature > I prefer the commands instead symbols - the parsing and processing symbols should be more complex than it is now. A psql parser is very simple - and any complex syntax enforces lot of code. \if_not Regards Pavel > \echo "feature xxx is needed, aborting" > \exit 2 > \fi > ... > > -- > Fabien > > > -- > Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-hackers >
