Ferret talk - Nov 2006 - usage and benefits of single-index with AAF

The documentation states:

"single_index: set this to true to let this class use a Ferret index  
that is shared by all classes having :single_index set to  
true. :store_class_name is set to true implicitly, as well as  
index_dir, so don?t bother setting these when using this option. the  
shared index will be located in index/<RAILS_ENV>/shared ."

[1] If I''m reading the code correctly, it seems that single-model  
searches will behave the same as before, and AAF/Ferret will add the  
extra column to the query for me. Is this correct?

[2] How can I take advantage of the single-index when doing multi- 
model searches? Through which model will I perform the query? Or do I  
need to do this with raw Ferret queries and not through AAF?

[3] Are there other advantages or gotchas that I''m missing?

Thanks,
John

On Thu, Nov 30, 2006 at 12:50:32PM -0500, John Bachir wrote:
[..]
> 
> [1] If I''m reading the code correctly, it seems that single-model
> searches will behave the same as before, and AAF/Ferret will add the  
> extra column to the query for me. Is this correct?
yep.
> [2] How can I take advantage of the single-index when doing multi- 
> model searches? Through which model will I perform the query? Or do I  
> need to do this with raw Ferret queries and not through AAF?
there''s a secret option called :models to find_by_contents, which you
can use to specify any additional models you want to search in. I just
committed a fix adding that piece of documentation, and a fix to set the
ferret_score attribute on results when using single_index.
> [3] Are there other advantages or gotchas that I''m missing?
generally the whole single_index thing seems to be less commonly used
and therefore is less tested in the wild.

Also with single_index each object in a result set is fetched with a
single call to find, which clearly is not acceptable if a search returns
a serious amount of results. Patches welcome ;-)

I''d normally suggest using the multi-index search feature as an
alternative to single_index (it''s possible to search across multiple
indexes at once with the multi_search method), but unfortunately this
yields segfaults with recent Ferret versions (i think >= 0.10.10).

cheers,

Jens

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