[openbeos] Re: queries on missing attributes

"Alexander G. M. Smith" <agmsmith@xxxxxxxxxx> wrote:
> Jonas Sundström wrote on Mon, 20 Dec 2004 14:23:50 +0100 CET:
> > Is there a way to make queries on missing attributes?
> 
> Since it needs an index to iterate over, you can use the file type to 
> just
> check the files you need, or even "name=*" to iterate over all files.  
> The
> query would be something like name=*&&attribute="", but that only 
> works for
> strings I think.  Or maybe you could try name=*&&attribute!=*

I was using (name=*)&&(something else) in my testing. IIRC it would 
only return files that had the attribute. I could be wrong though. 
Perhaps there's some boolean logic I haven't tested.

> I added a couple of operators in my RAM file system for testing 
> attribute
> existance, <>attribute for files including that attribute, and ><
> attribute
> for ones that don't have it (think of the > and < together making an 
> X shape
> to cross out the possibility of existance).  But since the query 
> language
> is implemented by each file system (some wasted effort there - the OS 
> should
> just provide indices, let library code do queries), those operators 
> are only
> in AGMSRAMFileSystem.

Could this happen in R1 or is it a clear R2 thing?

/Jonas Sundström.                 www.kirilla.com

Other related posts: