PFC wrote [01/28/05 7:08 PM]:
>
> First you should use a ltree type for the uri field :
Yes, it would be very good if I could use ltree rather than rolling my
own, but ltree doesn't meet my use requirements.
> - you write it foo.bar instead of /foo/bar
That is the problem: The point is to make look-up based on uri or
filesystem path very efficient.
> - there are operators on ltree types to express "is parent of", "is
> children of"
> - these operators are indexed
I have written similar pure-SQL functions for my parent/uri system,
though without the syntax shortcuts of the ltree operators.
> [...]
> Now about your update problem, when you rename foo.bar into
> foo.crum.bar you could, in a single update, replace all foo.bar by
> foo.crum.bar in all your table with the ltree operators and special
> functions.
That's an approach I hadn't considered. Hmmm, I'd have to read the ltree
C sources to see how it does this....
> And for your checks, you can add a CHECK on the url field to be sure
> it's equal to the url of the parent + the name of the current row.
> It'll make one more SELECT request, though.
Yes, I'd like to avoid extra selects as much as possible.
Thank you very much for your interaction -- very helpful.
--
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harrison@tbc.net
