Re: Inheritance...
Re: Inheritance...
- Subject: Re: Inheritance...
- From: Chuck Hill <email@hidden>
- Date: Thu, 8 May 2008 09:51:37 -0700
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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