Re: [Engine-devel] What type of DB inheritance to use?

----- Original Message ----- > On 05/12/2013 12:42 PM, Mike Kolesnik wrote: >> Hi All, >> >> I would like to have your opinions on which inheritance type to use in >> the DB. >> We are adding an "external provider" entity to the system which will be >> able to provide various resources (networks, hosts, etc). >> >> These providers will be distinguishable by "type". >> The basic definition of a provider contains: >> >> * name >> * description >> * url >> * type >> >> Some providers might need additional properties such as: >> >> * user >> * password > > what type of provider won't require authentication? Quantum provider in the 1st implementation will not require these fields. It will eventually require some sort of authentication, but not necessarily these fields, or only these fields.

> >> >> In Java this is easily represented by inheritance. >> >> In the DB however, there are 3 approaches that we can take: >> >> 1. No inheritance. >> This means that each type will wit in his own table, with no >> relation or re-use. >> 2. Single table inheritance. >> All types sit in a single table, and each has his corresponding >> columns. >> 3. Multiple table inheritance. >> Each type sists in his own table, where the PK is FK for the most >> basic table (providers). >> >> >> Pros for each approach: >> >> 1. None that I can think of. >> 2. No joins: >> Better performance >> Easier for developer to see the DB info >> Facilitate column reuse >> 3. Constraints can be set on each column >> >> Cons for each approach: >> >> 1. No reuse of DB entities + no compliance for column types >> Most cumbersome to query all providers >> 2. Can't put some constraints on non-base columns (esp. not null) >> 3. Joins are needed - opposite of the pros of 2. >> >> From personal experience, I find #2 to be better and easier to work >> with & maintain. >> >> What are your thoughts? >> >> Regards, >> Mike >> >> >> >> _______________________________________________ >> Engine-devel mailing list >> Engine-devel(a)ovirt.org >> http://lists.ovirt.org/mailman/listinfo/engine-devel >> > >