------=_Part_119211_1477841530.1368352381010 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit ----- Original Message -----
From: "Mike Kolesnik" <mkolesni@redhat.com> To: "engine-devel" <engine-devel@ovirt.org> 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 Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
</div></blockquote><div>You forgot to mention discriminator column a= t option 2 (how are you going to differ between sub types) which should be = indexed.</div><blockquote style=3D"border-left:2px solid #1010FF;margin-lef= t:5px;padding-left:5px;color:#000;font-weight:normal;font-style:normal;text= -decoration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;"><d= iv style=3D"font-family: times new roman, new york, times, serif; font-size= : 12pt; color: #000000"><div><div><div><ol><li><br></li><li>Multiple table = inheritance.<br>Each type sists in his own table, where the PK is FK for th= e most basic table (providers).<br></li></ol><div><br></div><div>Pros for e= ach approach:<br></div><div><ol><li>None that I can think of.<br></li><li>N= o joins:<br> Better performance<br> = ; Easier for developer to see the DB info<br> F= acilitate column reuse<br></li><li>Constraints can be set on each column<br= </li></ol></div></div></div></div><div>Cons for each approach:<br></div><d= iv><ol><li>No reuse of DB entities + no compliance for column types<br>Most= cumbersome to query all providers<br></li><li>Can't put some constraints o= n non-base columns (esp. not null)<br></li><li>Joins are needed - opposite = of the pros of 2</li></ol></div></div></blockquote><blockquote style=3D"bor= der-left:2px solid #1010FF;margin-left:5px;padding-left:5px;color:#000;font= -weight:normal;font-style:normal;text-decoration:none;font-family:Helvetica= ,Arial,sans-serif;font-size:12pt;"><div style=3D"font-family: times new rom= an, new york, times, serif; font-size: 12pt; color: #000000"><div><ol><li><= br></li></ol><div>From personal experience, I find #2 to be better and easi= er to work with & maintain.</div></div></div></blockquote><div>I think = it really depends on the use-case, but I also had better experience with 2.= </div><blockquote style=3D"border-left:2px solid #1010FF;margin-left:5px;pa=
------=_Part_119211_1477841530.1368352381010 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable <html><body><div style=3D"font-family: times new roman, new york, times, se= rif; font-size: 12pt; color: #000000"><br><div><br></div><hr id=3D"zwchr"><= blockquote style=3D"border-left:2px solid #1010FF;margin-left:5px;padding-l= eft:5px;color:#000;font-weight:normal;font-style:normal;text-decoration:non= e;font-family:Helvetica,Arial,sans-serif;font-size:12pt;"><b>From: </b>"Mik= e Kolesnik" <mkolesni@redhat.com><br><b>To: </b>"engine-devel" <en= gine-devel@ovirt.org><br><b>Sent: </b>Sunday, May 12, 2013 12:42:14 PM<b= r><b>Subject: </b>[Engine-devel] What type of DB inheritance to use?<br><di= v><br></div><div style=3D"font-family: times new roman, new york, times, se= rif; font-size: 12pt; color: #000000"><div>Hi All,<br></div><div><br></div>= <div>I would like to have your opinions on which inheritance type to use in= the DB.<br></div><div>We are adding an "external provider" entity to the s= ystem which will be able to provide various resources (networks, hosts, etc= ).<br></div><div><br></div><div>These providers will be distinguishable by = "type".<br></div><div>The basic definition of a provider contains:</div><di= v><ul><li> name</li><li>description</li><li>url</li><li>type</li></ul><div>= Some providers might need additional properties such as:<br></div><div><ul>= <li>user<br></li><li>password<br></li></ul><div>In Java this is easily repr= esented by inheritance.<br></div><div><br></div><div>In the DB however, the= re are 3 approaches that we can take:<br></div><div><ol><li>No inheritance.= <br>This means that each type will wit in his own table, with no relation o= r re-use.<br></li><li>Single table inheritance.<br>All types sit in a singl= e table, and each has his corresponding columns.</li></ol></div></div></div= dding-left:5px;color:#000;font-weight:normal;font-style:normal;text-decorat= ion:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;"><div style= =3D"font-family: times new roman, new york, times, serif; font-size: 12pt; = color: #000000"><div><div><br></div><div><br></div><div>What are your thoug= hts?<br></div></div><div><br></div><div>Regards,<br>Mike<br></div><div><br>= </div></div><br>_______________________________________________<br>Engine-d= evel mailing list<br>Engine-devel@ovirt.org<br>http://lists.ovirt.org/mailm= an/listinfo/engine-devel<br></blockquote><br></div></body></html> ------=_Part_119211_1477841530.1368352381010--