Re: Path lookup table (was: Re: Locking design (was Re: svn commit: r9885 - trunk/notes))

On Fri, 2004-05-28 at 11:06, Travis P wrote:
> On May 28, 2004, at 1:51 AM, Branko Čibej wrote:
>
> > BDB supports variable-length keys, but table-based databases (which we
> > want to support in future) are notoriously cranky about rejecting
> > such, and they're not very efficient in BDB, either. So the structure
> > of the index would have look like this:
> >
> > (dir-id, name, [txn-id]) -> info
>
> I'm not sure what you mean by cranky.

Well, it doesn't matter. There's a more important reason why we can't
have a lookup table by full pathname: it isn't compatible with O(1)
directory copies.

(We could have a *cache* table indexed by full path, as long as the
cache is populated in a lazy fashion and is of fixed size. Even then,
directory copies could be perceived as having a non-O(1) performance
impact because of their impact on the cache. Easier to avoid having any
DB tables indexed by full path.)

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Received on Fri May 28 18:04:12 2004