Re: Inheritance...
Re: Inheritance...
- Subject: Re: Inheritance...
- From: Chuck Hill <email@hidden>
- Date: Thu, 8 May 2008 10:11:21 -0700
On May 8, 2008, at 10:08 AM, David Avendasora wrote:
How will it work for Wonder's "Partial" Entities that are part of a
Vertical Inheritance structure on a full moon with Pluto in the
third house?
Yes.
Chuck
On May 8, 2008, at 12:51 PM, Chuck Hill wrote:
On May 8, 2008, at 7:14 AM, Florijan Stamenkovic wrote:
Besides the question below, I came up with another scenario
today... While it is true that performance should not be an issue
with the records in the inheritance tree, what about
relationships? I will have potentially thousands of records that
have two mandatory relationships to the leaf nodes, but defined in
the model as relationships to the root of the inheritance....
Those relationships will be used heavily, and I will need to pre-
fetch them. So, when that happens, what is going on in the
database, when using horizontal inheritance? There is an FK in the
table I am fetching on, but that FK might resolve to a PK in any
of the inheritance tables, no? Sounds kind of expensive... Or is
there something magical going on?
For Horizontal, it will issue one select for each leaf entity
(IIRC). Single table is much more efficient in this scenario.
Chuck
F
On May 07, 2008, at 22:24, Florijan Stamenkovic wrote:
Thanks everyone from preventing me to learn the hard way...
Apparently my choices are single-table or horizontal.
A question: assuming I intend to perform individual fetches for
each entity anyway, that there will be no direct fetching on the
root entity, and that there will be maybe 100 records in the
total hierarchy, is there something else against using
horizontal? It seems that, considering these things, it might be
profitable to keep the db clean, even though at the moment only
EOF will deal with it... I mean, for 100ish records in total, how
bad can performance get???
30+ columns in a table just hurts me in the stomach area :)
Though, I guess I could, arghhh, get over it...
Flor
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