Re: The wisdom of the object mentors (Was: Searching OO Associations with RDBMS Persistence Models)

On 2006-06-21 15:13:43 -0500, "topmind" <topmind@xxxxxxxxxxxxxxxx> said:


Robert Martin wrote:
On 2006-06-13 00:14:58 -0400, frebe73@xxxxxxxxx said:

How do you find "use relationship tables in programming language"
inconvenient?

If I want to traverse a deeply interconnected graph of data, in which
each node contains a reference to other nodes, then relationship tables
queried with SQL much less convenient than node data structures that
point to other nodes.


Can you provide a demonstration on why it is allegedly less convenient?
Note that I have nothing against creating app-specific functions for
common activities, such as GetSurroundingNodes(depthLevel). SQL can
provide some easy solutions to problems that may be time-consuming to
roll by hand such as removing duplicates, cross-referencing, summing,
etc.

Consider circuit board layout software. All the traces, conectors, feed-thrus, solder masks, silk screens, etc. Just the traces are a set of line segments that form a graph of edges and nodes. Now write an algorhithm that notes where the bypass capacitors are, and also where the noisy components are, and makes sure that the noise is properly bypassed.

To do this you are going to have to walk the graph of traces over and over again. This is better done in ram, than through repeated tiny SQL queries, each of which gives you the next few line segments.
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Robert C. Martin (Uncle Bob)  | email: unclebob@xxxxxxxxxxxxxxxx
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