2016-12-28 18:54 GMT+01:00 Jim Nasby <jim.na...@bluetreble.com>: > On 12/28/16 7:16 AM, Pavel Stehule wrote: > >> ** The real problem is that we have no mechanism for allowing a PL's >> language/syntax/API to move forward without massive backwards >> compatibility problems. ** >> >> >> We have not, but there are few possibilities: >> >> 1. enhance #option command >> 2. we can introduce PRAGMA command >> https://en.wikipedia.org/wiki/Ada_(programming_language)#Pragmas >> <https://en.wikipedia.org/wiki/Ada_%28programming_language%29#Pragmas> >> > > I wanted to break this out separately, because IMO it's the real heart of > the matter. > > I think it would be silly not to allow a global setting of compatibility. > You certainly don't want to force people to stick magic keywords in their > code forevermore. > > To that end, would GUCs be a workable answer here? That should give you > the ability to control incompatibilities at a function, user, database and > global level. It would also allow you to chose between raising a WARNING vs > a FATAL. >
GUC are fragile - the source code and settings can be separated. Our #option is more robust, because source code holds all flags required for execution. So I would to see a mechanism, that will be strongly joined with code. Using function assigned GUC is similar, but it is looking less robust - and some editors can forgot this information. Lot of issues we can solved by plpgsq.extra_error, extra_warnings - but probably not all - for example issue of FOUND variable or introducing new auto variable ROW_COUNT. PLpgSQL - PL/SQL is safe - it propose the statement GET DIAGNOSTICS, but I understand so isn't funny to write more and more GET DIAGNOSTICS rc = ROW_COUNT; So some shortcuts can be nice, but there is risk, so this shortcut breaks existing code, and the costs/benefits are individual. There cannot be 100% agreement ever. So some customisation should be good. > > I realize we've had some bad experiences with compatibility GUCs in the > past, but I'd argue we've also had some good experiences. I see that > add_missing_from is now completely gone, for example, presumably with no > complaints. There's probably several other compatibility GUCs we could > remove now. > > -- > Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX > Experts in Analytics, Data Architecture and PostgreSQL > Data in Trouble? Get it in Treble! http://BlueTreble.com > 855-TREBLE2 (855-873-2532) >
