Re: [HACKERS] Make subquery alias optional in FROM clause
От | Nico Williams |
---|---|
Тема | Re: [HACKERS] Make subquery alias optional in FROM clause |
Дата | |
Msg-id | 20170223163019.GC30233@localhost обсуждение исходный текст |
Ответ на | Re: [HACKERS] Make subquery alias optional in FROM clause (Bernd Helmle <mailings@oopsware.de>) |
Список | pgsql-hackers |
On Thu, Feb 23, 2017 at 10:37:16AM +0100, Bernd Helmle wrote: > Am Mittwoch, den 22.02.2017, 22:17 -0500 schrieb Tom Lane: > > [ shrug... ] Well, I won't resist this hard as long as it's done > > competently, which to me means "the subquery name doesn't conflict > > with > > anything else". Not "it doesn't conflict unless you're unlucky > > enough > > to have used the same name elsewhere". There are a couple ways we > > could > > achieve that result, but the submitted patch fails to. > > Right, i'm going to give it a try then. Currently i see these options: > > * Validate any generated alias against a list of explicit alias names. > > This means we have to collect explicit alias names in, say a hashtable, > and validate a generated name against potential collisions and retry. > Or better, generate the name in a way that doesn't produce a collision > with this list. There's another option: * Gensym an alias name, and if the compilation fails with that alias name as a conflict, try again with a new gensym'edname. > * Don't force/generate an alias at all. That seems like a lot of work. Nico --
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