Re: Hypothetical questions

Comments inline

> 1. BLOBs -- ... If you had the chance to redesign your data model
> from scratch, would you continue to store your BLOBs internally, or
> would you look at storing them outside the database and why?

It depends. If the data is something that needs to be stored, kept and retreived for legal reasons now and years down the road, like an Acrobat .pdf contract - storing as a BFILE may be a very bad idea. Otherwise storing as a BFILE has always worked out to be the least amount of work for me. Either or, both the logical and physical model, in my mind would 'look' the same. What is different is the available access to the data via the DBMS_LOB package, storage consumption and recovery options, as well as performance - which all depend on the usage of the data. For store and forget data, (very little retreival/modification) I have not discovered any great performance differences.

> 3) Char vs. Varchar2? I have heard the following arguments for char
> vs. varchar2:
> a) argument 1: You should always use varchar because you save
> space.
> b) argument 2: Use char when all possible values stored in a column
> are about the same length, use varchar when they can have widely
> different lengths.
> c) argument 3: Use char instead of varchar, because varchar can
> cause a row to span multiple blocks, thus taking longer to retrieve
> data.
>
> Which philosophy (a, b, or c, or another different philosophy
> altogether) would you choose when designing a data model and why?

It depends. Generally #1, though. I don't understand the validity in stating #2. #3 is not pertinent on whether the data is volitale or not. For the most part, the person doing the physical data modeling will have worked through these issues, using their experience. There just isn't any fixed philosophy to answer your question succinctly. There are simply more dimensions to consider than the question you ask alone. Received on Mon Dec 11 2000 - 22:35:59 CST