Interesting node -- but I see a problem brewing with the rows that have 'distance to the next node' > 1. That's data that can be inferred, and if it gets entered wrong, or if someone monkeys with the database, the whole thing comes crashing down.

However, I think I understand what you're doing -- you're trying to pre-cook as much as possible for performance. Thus I'd probably have two tables: the first would have just nearest neighbours, and the second would have all of the inferred data. Then you could use a UNION to get the same performance as your original design.

Just some idle thoughts over my morning coffee.

Alex / talexb / Toronto

"Groklaw is the open-source mentality applied to legal research" ~ Linus Torvalds

In reply to Re: Trees in SQL, adjacency lists and sorting. by talexb
in thread Trees in SQL, adjacency lists and sorting. by BUU

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.