[Nitro] OG vs Active Record
john at oxyliquit.de
Fri Aug 24 14:00:39 EDT 2007
> I can appreciate the convinience of using adjacencies. But
> there are as you suggest other criteria.
I never said I'd be using adjacency lists. ;)
Right now I'm more on the track on materialized path, which
(with help from postgres) has really good performance for all
operations I need and at the same time is conceptually easy.
> Where I work there's a tree of about 38,000 nodes changing a
> few times a day. The amount of hand-editing that goes on is
> near nil, though the simplicity of adjacencies has been useful
> in debugging.
Yeah, debugging, good example. Although an extensive test suite
covering all that might be enough of a safety net for relations
and can provide good enough information when stuff goes wrong...
> The simplicity of adjacencies is a much larger factor if your
> tree is small and there are good reasons to take the short-cut
> of manual edits or manual generation.
>The broadest solution would be maintaining the adjacency list
> *alongside* the nested set. Simply add a parent_id field to
> each node. You can hand-insert a node, and run a script to
> have the system place it in the nested set.
I think the NestedSets implementation within Og has the parent
saved too. That could be a starting place for someone who wants
to investigate on that further.
> Alternatively, you can have a utility script that regenerates
> the adjacency list after an insert.
I heard some professionals use that two layer approach. They
insert/update only the adjacency list, which is quite quick for
some operations. Then they just regenerate a nested-sets table
with the new information for fast selects.
Too bad I don't have too much experience yet with real life
high-performance stuff with huge databases. Thanks Robert for
also replying here. :)
Feel the love
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