I have started reading some books about data warehouses and star schema, and one thing keeps tripping me up.
In this context, it seems that the norm is to use the phrase "level of detail" opposite to what I am accustomed to seeing.
(i.e. that "lower" level of detail is more detailed)
Usually, in my experience, higher level of detail means more detailed. (graphics being a good example)
Is it just me or does that rub anyone else wrong?
Edited by: Seedyman on Feb 14, 2013 1:02 PM
Dom Brooks wrote:
Depends on context.
What do you think when someone says "give me a high level overview"?
No higher ... higher ... helicopter view...
I understand the difference, it just took me a while to shift gears in my brain.
When they talk about what level of detail to build warehouse tables to, it was not readily apparent what sense of level of detail was meant immediately.
I was confused when they first said build fact tables to the lowest level of detail possible, then figured it out when they said later that one can never report on a lower level of detail than the fact table, or something like that.
When processing graphical data/objects you talk about things very similarly, only the sense of the words is opposite. With high levels of detail meaning much larger storage and processing requirements.
Yeah, it's kind of ambiguous.
I read a restaurant review where the author used the phrases "sub-par" and "below par".
The reviewer clearly didn't like the place but in golf (where par is frequently used) "below par" is a good thing.
You will have to get used to the convention. This is generally accepted convention.
Aggregating records by month is a higher level aggregation. (e.g. Total Sales for the month)
Reporting daily records (reporting each individual sale transaction) is a lower level -- a level that contains more detail and is more granular ("granularity" is another term you'll have to learn).
Hemant K Chitale