On Sun, Nov 17, 2013 at 6:57 PM, Tony Theodore <tony.theod...@gmail.com>wrote:
> > On 15 Nov 2013, at 8:04 pm, Chris Travers <chris.trav...@gmail.com> wrote: > > > > In general, if you don't know you need composite types, you don't want > them. You have basically three options and the way you are doing it is the > most typical solution to the problem > > The current way is much easier since I discovered the “JOIN ... USING(..)” > syntax and I’m tempted to try natural joins. > > > Having experience with table inheritance and composite types in tuples, > I will say the former has fewer sharp corners than the latter. > > > > Where composite types really work well is where you want to add > functions which take the type as input. In essence you can develop some > very sophisticated models with them, but you probably would not use them > for storage unless you have other considerations in mind. > > Thanks for that, I’ve done some reading on inheritance and it looks like I > can create an empty parent table that acts like a column definition > template. This also automatically creates a type that can be used in > functions which sounds like what I’m after. There are also scenarios where > “product” is a combination of “level" and “id” (where “level” can be things > like brand/category/sku) and I’d like to use the same calculations > regardless of where it sits in the hierarchy. > I haven't done work with this so I am not 100% sure but it seems to me based on other uses I have for table inheritance that it might work well for enforcing interfaces for natural joins. The one caveat I can imagine is that there are two issues that occur to me there. 1. If you have two child tables which add a column of the same name, then your centralized enforcement gets messed up and you have a magic join which could take a while to debug.... 2. The same goes if you have two child tables which also inherit a different parent table for a different natural join.... To be honest I think being explicit about joins is usually a very good thing. Best Wishes, Chris Travers > > Cheers, > > Tony > > -- Best Wishes, Chris Travers Efficito: Hosted Accounting and ERP. Robust and Flexible. No vendor lock-in. http://www.efficito.com/learn_more.shtml
