Physical vs Logical modelling = Mixed tapes vs. iTunes playlists
We were discussing the agility that HANA delivers with a partner recently, and searching for powerful metaphors for describing it to business stakeholders. There are a number of blogs around the benefits that agility bring, as well as the drivers for this agility in both early project stages like requirements gathering, design and development, as well as later stages including implementation, test, documentation and change management.
Although the speed and computational power enable some of this agility by delayering the BI process, a lot of the agility is also delivered by the use of logical instead of physical modelling. This is also a key differentiator, and one that deserves some more attention. I may be showing my age here, but we’ll use the analogy of creating mixed tapes vs. creating iTunes playlists…
The creation of a mixed tape was a labour of love… It involved many hours of recording from your vinyl records or for those of us who had dual-cassette tape decks, from tape to tape. You had to think carefully about the entire tape – the mood, the order of the songs, the length of each song and the total tape length. Once you had finished your masterpiece, changing it was very difficult. If you wanted to replace a song, you needed to find another song that was the same length or shorter (and if it was shorter, decide whether you could live with the blank spot in the tape). Reordering the tracks…. didn’t happen.
Now let’s consider the itunes playlist. You store a single copy of all the songs or tracks – your library of songs. To create a playlist, you just drag and drop into a logical container. You don’t copy the music – you still only have a single copy of the track on your itunes library. This is true no matter how many playlists use that same track.
If you need to, you can easily see which playlists include any particular track (let’s call that musical compliance). If you discover that you need to get rid of a track for any reason (like you have grown out of your ABBA or other embarrassing stage of musical development), you delete it once from the library.
What are the other tasks that become easier?
- Changing the order of tracks
- Duplicating playlists and then amending them
- Mixing multiple playlists to create a whole evening’s worth of music
- Having different ‘logical’ views of your tracks (alphabetical, by artist, by genre, by frequency of listening to)
- Seeing which tracks are never played, and deciding if you want to keep them
- …. Almost forgot documentation – writing down all the songs, in order, checking spelling, all in neat handwriting. Any changes – tipex if you’re ready to compromise, a new written playlist if not.
And of course, the building of a playlist takes minutes, rather than the 10+ hours that it used to take to create a great mixed tape. Which means that the time-to-value is much shorter, although we didn’t think of it in those terms – maybe it should be time-to-enjoyment or time-to-tunes. And to answer your next question, no, these are not my mixed tapes.
How far will this analogy go? Where are its limitations? I’d like to hear your thoughts either way…
Many thanks to Brian Raver, who introduced me to the metaphor. Blog originally posted on saphana.com