Hash on a subset of metadata?

[thobson]

Is it possible to generate an id using only a subset of the metadata?

In my case I'm storing some metadata along with the documents but I don't need to filter on these fields.

I also don't want the fields to form part of the id hash because otherwise changing the metadata will result in a new id.

It's not a big deal, I can also store the "raw" documents in a DB and use haystack just for search.

Thanks

Toby