----- Original Message ----- > From: "Liran Zelkha" <[email protected]> > To: "Yair Zaslavsky" <[email protected]> > Cc: "engine-devel" <[email protected]> > Sent: Sunday, May 12, 2013 1:19:07 PM > Subject: Re: [Engine-devel] What type of DB inheritance to use? > > Hi > > From my experience, single table inheritance quickly grows into something > unmanagable, as more and more (child related) fields are added, each line > has a few relevant attributes, and a long list of NULL values. > I would go with option 3. With materialized views, the costs of joins can be > eliminated.
+1 > > > On Sun, May 12, 2013 at 12:53 PM, Yair Zaslavsky < [email protected] > > wrote: > > > > > > > > > From: "Mike Kolesnik" < [email protected] > > To: "engine-devel" < [email protected] > > Sent: Sunday, May 12, 2013 12:42:14 PM > Subject: [Engine-devel] What type of DB inheritance to use? > > 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 > > 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. > You forgot to mention discriminator column at option 2 (how are you going to > differ between sub types) which should be indexed. > > > > > > 1. > 2. 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 > > > > > > 1. > > From personal experience, I find #2 to be better and easier to work with & > maintain. > I think it really depends on the use-case, but I also had better experience > with 2. > > > > > > What are your thoughts? > > Regards, > Mike > > > _______________________________________________ > Engine-devel mailing list > [email protected] > http://lists.ovirt.org/mailman/listinfo/engine-devel > > > _______________________________________________ > Engine-devel mailing list > [email protected] > http://lists.ovirt.org/mailman/listinfo/engine-devel > > > > _______________________________________________ > Engine-devel mailing list > [email protected] > http://lists.ovirt.org/mailman/listinfo/engine-devel > _______________________________________________ Engine-devel mailing list [email protected] http://lists.ovirt.org/mailman/listinfo/engine-devel
