Ferret talk - Apr 2008 - Pagination, sorting and conditions: the combination is breaking my search results...

Hi

I have a problem with a search where i want to get some results according to
some conditions, sort the results, and then paginate over the sorted
collection.

My search looks like this:

      @results  = TeachingObject.find_with_ferret(search_term,
                        #(ferret) options
                        {:page => options[:page],
                        :per_page => options[:per_page],
                        :sort => Ferret::Search::SortField.new(:asset_count,
:type => :integer, :reverse => true )},
                        #find options
                        { :conditions => ["id in (?)", @ids] } )

where @ids is an array of ids from which the results must come (ie a
collection of ''allowed'' results of which @results will be a
subset): often
the search term is set to * to get all of this collection in @results.
'':asset_count'' is an untokenized ferret field that stores
integers.

Through debugging and experimenting, i''ve observed the following:

   - The overall results set, without sorting/pagination, is correct
   (therefore :conditions is being taken into account).
   - If :per_page is set to be so large that no pagination is required, then
   the sorting occurs properly (therefore sorting is being taken into account)
   - If :per_page is reduced so that pagination is required, then the
   sorting of the overall set breaks: it seems as if the results are ordered by
   id, then paginated.
   - However, on every individual page, the results are sorted properly for
   that page, ie each page-size subset is internally sorted.
   - If i sort on a different untokenized field,  the problem persists.

It seems as if the pagination is happening and THEN the sorting is
happening, which obviously doesn''t give the expected results.  This is
just
a theory on my part though.

Can anyone tell me how to fix this problem?  I''ve been gnashing my
teeth
over it for over a day now and can''t find any solutions...

thanks
max
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Hi Max,

thanks for your detailed report. Might well be that I broke one or more
of the various combinations of pagination / sorting / active record
conditions (where you might specify :order, too, btw) in trunk.

I''ll look into it asap.

Cheers,
Jens

On Fri, Apr 25, 2008 at 11:45:30AM +0100, Max Williams
wrote:
> Hi
> 
> I have a problem with a search where i want to get some results according
to
> some conditions, sort the results, and then paginate over the sorted
> collection.
> 
> My search looks like this:
> 
>       @results  = TeachingObject.find_with_ferret(search_term,
>                         #(ferret) options
>                         {:page => options[:page],
>                         :per_page => options[:per_page],
>                         :sort =>
Ferret::Search::SortField.new(:asset_count,
> :type => :integer, :reverse => true )},
>                         #find options
>                         { :conditions => ["id in (?)", @ids] }
)
> 
> where @ids is an array of ids from which the results must come (ie a
> collection of ''allowed'' results of which @results will be
a subset): often
> the search term is set to * to get all of this collection in @results.
> '':asset_count'' is an untokenized ferret field that stores
integers.
> 
> Through debugging and experimenting, i''ve observed the following:
> 
>    - The overall results set, without sorting/pagination, is correct
>    (therefore :conditions is being taken into account).
>    - If :per_page is set to be so large that no pagination is required,
then
>    the sorting occurs properly (therefore sorting is being taken into
account)
>    - If :per_page is reduced so that pagination is required, then the
>    sorting of the overall set breaks: it seems as if the results are
ordered by
>    id, then paginated.
>    - However, on every individual page, the results are sorted properly for
>    that page, ie each page-size subset is internally sorted.
>    - If i sort on a different untokenized field,  the problem persists.
> 
> It seems as if the pagination is happening and THEN the sorting is
> happening, which obviously doesn''t give the expected results. 
This is just
> a theory on my part though.
> 
> Can anyone tell me how to fix this problem?  I''ve been gnashing my
teeth
> over it for over a day now and can''t find any solutions...
> 
> thanks
> max
> _______________________________________________
> Ferret-talk mailing list
> Ferret-talk at rubyforge.org
> http://rubyforge.org/mailman/listinfo/ferret-talk
-- 
Jens Kr?mer
webit! Gesellschaft f?r neue Medien mbH
Schnorrstra?e 76 | 01069 Dresden
Telefon +49 351 46766-0 | Telefax +49 351 46766-66
kraemer at webit.de | www.webit.de
 
Amtsgericht Dresden | HRB 15422
GF Sven Haubold

Fantastic, thanks Jens.

BTW, I can''t :order by :asset_count as it''s a method, rather
than an
instance variable.  I wish AR::find would let me order by method returns.

While we''re talking, i just tried another way of searching and found
another
bit of weirdness:  instead of find_with_ferret, i tried using

ActsAsFerret::find(term, class_array) instead, like so:

       #sorting/pagination is broken here
       @results = ActsAsFerret::find(search_term, [TeachingObject],
                      #(ferret) options
                      { :page => options[:page],
                        :per_page => options[:per_page],
                        :sort => Ferret::Search::SortField.new(:asset_count,
:type => :integer, :reverse => true )
                      },
                      #find options - need to specify conditions for each
searched class individually
                      {:conditions => { :teaching_object => ["id in
(?)",
@ids] } }
                   )

This gave exactly the same results as the previous search.  However, when i
added another class to the search, it works!

       #this works!
       @results = ActsAsFerret::find(search_term, [TeachingObject,
LearningObject],
                      #(ferret) options
                      { :page => options[:page],
                        :per_page => options[:per_page],
                        :sort => Ferret::Search::SortField.new(:asset_count,
:type => :integer, :reverse => true )
                      },
                      #find options - need to specify conditions for each
searched class individually
                      {:conditions => { :teaching_object => ["id in
(?)",
@ids],
                                               :learning_object => ["id
in
(?)", @ids] } }
                   )

So, this works while the previous doesn''t.  It so happens in this case
that
LearningObject is a ''sister'' class of TeachingObject (they
both extend a
class called Resource), where both are saved in a table called resources
using STI, and at the moment i don''t actually have any LearningObject
records, so adding LearningObject doesn''t harm my results.  Obviously
though
this isn''t a nice workaround.

Sorry to pile bug reports on you, i just mention it in case it''s
relevant.
:/

Thanks a lot
max

2008/4/25 Jens Kraemer <kraemer at webit.de>:
> Hi Max,
>
> thanks for your detailed report. Might well be that I broke one or more
> of the various combinations of pagination / sorting / active record
> conditions (where you might specify :order, too, btw) in trunk.
>
> I''ll look into it asap.
>
> Cheers,
> Jens
>
> On Fri, Apr 25, 2008 at 11:45:30AM +0100, Max Williams wrote:
> > Hi
> >
> > I have a problem with a search where i want to get some results
according
> to
> > some conditions, sort the results, and then paginate over the sorted
> > collection.
> >
> > My search looks like this:
> >
> >       @results  = TeachingObject.find_with_ferret(search_term,
> >                         #(ferret) options
> >                         {:page => options[:page],
> >                         :per_page => options[:per_page],
> >                         :sort =>
> Ferret::Search::SortField.new(:asset_count,
> > :type => :integer, :reverse => true )},
> >                         #find options
> >                         { :conditions => ["id in (?)",
@ids] } )
> >
> > where @ids is an array of ids from which the results must come (ie a
> > collection of ''allowed'' results of which @results
will be a subset):
> often
> > the search term is set to * to get all of this collection in @results.
> > '':asset_count'' is an untokenized ferret field that
stores integers.
> >
> > Through debugging and experimenting, i''ve observed the
following:
> >
> >    - The overall results set, without sorting/pagination, is correct
> >    (therefore :conditions is being taken into account).
> >    - If :per_page is set to be so large that no pagination is
required,
> then
> >    the sorting occurs properly (therefore sorting is being taken into
> account)
> >    - If :per_page is reduced so that pagination is required, then the
> >    sorting of the overall set breaks: it seems as if the results are
> ordered by
> >    id, then paginated.
> >    - However, on every individual page, the results are sorted
properly
> for
> >    that page, ie each page-size subset is internally sorted.
> >    - If i sort on a different untokenized field,  the problem
persists.
> >
> > It seems as if the pagination is happening and THEN the sorting is
> > happening, which obviously doesn''t give the expected results.
This is
> just
> > a theory on my part though.
> >
> > Can anyone tell me how to fix this problem?  I''ve been
gnashing my teeth
> > over it for over a day now and can''t find any solutions...
> >
> > thanks
> > max
>
> > _______________________________________________
> > Ferret-talk mailing list
> > Ferret-talk at rubyforge.org
> > http://rubyforge.org/mailman/listinfo/ferret-talk
>
> --
> Jens Kr?mer
> webit! Gesellschaft f?r neue Medien mbH
> Schnorrstra?e 76 | 01069 Dresden
> Telefon +49 351 46766-0 | Telefax +49 351 46766-66
> kraemer at webit.de | www.webit.de
>
> Amtsgericht Dresden | HRB 15422
> GF Sven Haubold
> _______________________________________________
> Ferret-talk mailing list
> Ferret-talk at rubyforge.org
> http://rubyforge.org/mailman/listinfo/ferret-talk
>
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Hello Jens,

I think I know what''s going on here, because our descending sort 
searches are broken too and I have started to investigate what''s
causing
the problem and trying to fix it. I have a January ''08 version of the 
trunk. I believe it''s changed quite a lot since that time.

Jens, I don''t think it''s anything you "broke" but
rather an artifiact of
how MySQL works. At least, I''m using MySQL and this is the behaviour I 
see.

I created 6 records, whose ids are 1 to 6 in my database. I am 
paginating on every 5 records. In my reverse sort I would expect to see 
records 6, 5, 4, 3, 2 on page 1 of the results. And id 1 on page 2 of 
the results.

What I see is a method called ar_find_by_contents. It calls 
find_id_by_content that returns an array that in turn calls ferret. The 
array that comes back from ferret is actually correctly sorted:

6 0.928179502487183
5 0.928179502487183
4 0.928179502487183
3 0.928179502487183
2 0.928179502487183
1 0.928179502487183

The first number is the id, the second is the rank.

Now what happens is ar_find_by_contents calls retrieve_records. And 
retrieve_records produces a SELECT statement like so:

SELECT * FROM model WHERE id IN (6, 1, 2, 3, 4, 5) LIMIT 0, 5

It took me a while to figure out that things are being passed around as 
a hash, and hence the wacky order of the ids in the IN clause. Now the 
problem with this statement  is that MySQL doesn''t return records in
the
order that the ids appear in the IN clause. MySQL returns records in the 
order of the Primary Key on the table, which happens to be the id 
column. So MySQL is returning records 1, 2, 3, 4, 5, 6, in that order. 
Then the LIMIT clause kicks in and truncates the results to 1 through 5.

Now the rest of ar_find_by_contents valiantly tries to order the AR 
results with the rank returned by ferret (my first table above). The 
problem is, record 6, the youngest, is no longer in the results because 
LIMIT took it out. So AAF sorts records 1 through 5 descending.

Following along we can see how page two returns only record 6. On page 
two, the limit changes to

SELECT * FROM model WHERE id IN (6, 1, 2, 3, 4, 5) LIMIT 5, 5

Once again, My SQL returns records 1, 2, 3, 4, 5, 6, but this time the 
limit returns only the last record, id 6. And then AAF sorts that 
descending.

I working on a patch for the version I have by making MySQL return only 
the correct set of records in the first place. In other words, ensuring 
that the only ids present in the IN clause are the ones that should 
appear on page 1 of the results, or page 2, or pane N.

So my  AR query for page 1 looks like

SELECT * FROM model WHERE id IN (6, 5, 4, 3, 2) LIMIT 0, 5

and the AR query for page 2 looks like

SELECT * FROM model WHERE id IN (1) LIMIT 0, 5

I got it working, but in the process have made every other search, not 
work. Funny. I''m sure I''ll figure it out.

Anyway, Jens, that''s the gist of the problem at least how it relates to
MySQL. Other databases may vary.

Regards
Sheldon Maloff
veer.com


Jens Kraemer wrote:
> Hi Max,
> 
> thanks for your detailed report. Might well be that I broke one or more
> of the various combinations of pagination / sorting / active record
> conditions (where you might specify :order, too, btw) in trunk.
> 
> I''ll look into it asap.
> 
> Cheers,
> Jens
-- 
Posted via http://www.ruby-forum.com/.

Sheldon/Jens,

Any chance that this has been figured out and patched?

Great analysis Sheldon!

Jeff


On Thu, May 1, 2008 at 7:24 PM, Sheldon Maloff <smaloff at veer.com>
wrote:
> Hello Jens,
>
> I think I know what''s going on here, because our descending sort
> searches are broken too and I have started to investigate what''s
causing
> the problem and trying to fix it. I have a January ''08 version of
the
> trunk. I believe it''s changed quite a lot since that time.
>
> Jens, I don''t think it''s anything you "broke"
but rather an artifiact of
> how MySQL works. At least, I''m using MySQL and this is the
behaviour I
> see.
>
> I created 6 records, whose ids are 1 to 6 in my database. I am
> paginating on every 5 records. In my reverse sort I would expect to see
> records 6, 5, 4, 3, 2 on page 1 of the results. And id 1 on page 2 of
> the results.
>
> What I see is a method called ar_find_by_contents. It calls
> find_id_by_content that returns an array that in turn calls ferret. The
> array that comes back from ferret is actually correctly sorted:
>
> 6 0.928179502487183
> 5 0.928179502487183
> 4 0.928179502487183
> 3 0.928179502487183
> 2 0.928179502487183
> 1 0.928179502487183
>
> The first number is the id, the second is the rank.
>
> Now what happens is ar_find_by_contents calls retrieve_records. And
> retrieve_records produces a SELECT statement like so:
>
> SELECT * FROM model WHERE id IN (6, 1, 2, 3, 4, 5) LIMIT 0, 5
>
> It took me a while to figure out that things are being passed around as
> a hash, and hence the wacky order of the ids in the IN clause. Now the
> problem with this statement  is that MySQL doesn''t return records
in the
> order that the ids appear in the IN clause. MySQL returns records in the
> order of the Primary Key on the table, which happens to be the id
> column. So MySQL is returning records 1, 2, 3, 4, 5, 6, in that order.
> Then the LIMIT clause kicks in and truncates the results to 1 through 5.
>
> Now the rest of ar_find_by_contents valiantly tries to order the AR
> results with the rank returned by ferret (my first table above). The
> problem is, record 6, the youngest, is no longer in the results because
> LIMIT took it out. So AAF sorts records 1 through 5 descending.
>
> Following along we can see how page two returns only record 6. On page
> two, the limit changes to
>
> SELECT * FROM model WHERE id IN (6, 1, 2, 3, 4, 5) LIMIT 5, 5
>
> Once again, My SQL returns records 1, 2, 3, 4, 5, 6, but this time the
> limit returns only the last record, id 6. And then AAF sorts that
> descending.
>
> I working on a patch for the version I have by making MySQL return only
> the correct set of records in the first place. In other words, ensuring
> that the only ids present in the IN clause are the ones that should
> appear on page 1 of the results, or page 2, or pane N.
>
> So my  AR query for page 1 looks like
>
> SELECT * FROM model WHERE id IN (6, 5, 4, 3, 2) LIMIT 0, 5
>
> and the AR query for page 2 looks like
>
> SELECT * FROM model WHERE id IN (1) LIMIT 0, 5
>
> I got it working, but in the process have made every other search, not
> work. Funny. I''m sure I''ll figure it out.
>
> Anyway, Jens, that''s the gist of the problem at least how it
relates to
> MySQL. Other databases may vary.
>
> Regards
> Sheldon Maloff
> veer.com
>
>
> Jens Kraemer wrote:
> > Hi Max,
> >
> > thanks for your detailed report. Might well be that I broke one or
more
> > of the various combinations of pagination / sorting / active record
> > conditions (where you might specify :order, too, btw) in trunk.
> >
> > I''ll look into it asap.
> >
> > Cheers,
> > Jens
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Ferret-talk mailing list
> Ferret-talk at rubyforge.org
> http://rubyforge.org/mailman/listinfo/ferret-talk
>


-- 

Jeff Webb
jeff at boowebb.com
http://boowebb.com/
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Hi folks,

On 09.07.2008, at 06:01, Jeff Webb wrote:
> Sheldon/Jens,
>
> Any chance that this has been figured out and patched?
I just committed a fix to this problem to trunk, so pagination with  
sorting and AR conditions should work now.


cheers,
Jens

--
Jens Kr?mer
http://www.jkraemer.net/ - Blog
http://www.omdb.org/     - The new free film database

Hi Jens/all

I''ve been playing with latest version, and it seems that the
combination of
AR conditions, paginating and AR order (eg ":order => "name")
seems to be
fine now, even on our server, which was were it was broken before (it always
worked locally, weirdly).

However, i''ve just tried it with results that are sorted by ferret on
the
basis of their boost score, and it seems broken.

I''m sorry i don''t have any tests set up but if i walk through
an example can
anyone see something that maybe i''m doing wrong?  Or shed any light?

I use AR conditions to filter the results through a set of ids that an
individual user is allowed to view.  I just have a method User#allowed_ids
for this that returns an array of integers.  For the purpose of
illustration, though, let''s say that the allowed ids are everything
between
1000 & 2000.
allowed_ids = (1000..2000).to_a
=> [1000, 1001, 1002, etc, 2000]

For a particular search (on ''rhythm'') i get these results back
- the order
is the order calculated by ferret/aaf on the basis of boost values:
i''ve
collected them by id for clarity.  In this example i''ve set a big
per_page
to get all the results.
>> ActsAsFerret::find("rhythm", [TeachingObject],{ :page =>
1, :per_page =>
1000 }, {} ).collect(&:id)
=> [4038, 698, 4039, 1830, 1831, 1826, 1832, 1825, 1833, 411, 1834, 702,
1827, 1689, 1680, 1688, 1679, 1686, 1684, 1676, 2129, 2130, 2131, 1858,
1859, 1860, 1861, 1865, 2132, 2141, 2345, 2350, 2352, 2353, 2356, 2360,
2362, 2366, 2368, 2371, 2372, 2373, 2376, 2377, 2378, 2384, 2385, 2389,
2407, 2414, 2417, 2419, 2427, 2428, 2438, 2439, 2458, 2459, 2473, 2474,
2475, 2477, 2478, 2133, 2349, 2361, 2363, 2365, 2370, 2375, 2383, 2386,
2392, 2415, 2430, 2431, 2440, 2441, 2442, 2472, 2142, 3751, 2161, 1236]

Now, when i apply the condition of only being in the allowed ids, i''d
expect
the remaining ids to be in the same order as above, and that is in fact the
case:
>> ActsAsFerret::find("rhythm", [TeachingObject],{ :page =>
1, :per_page =>
1000 }, {:conditions => ["id in (?)", allowed_ids] }
).collect(&:id)
=> [1830, 1831, 1826, 1832, 1825, 1833, 1834, 1827, 1689, 1680, 1688, 1679,
1686, 1684, 1676, 1858, 1859, 1860, 1861, 1865, 1236]

Just to check, let''s do the original again (with no AR conditions) and
just
do set intersection with the allowed_ids
>> ActsAsFerret::find("rhythm", [TeachingObject],{ :page =>
1, :per_page =>
1000 }, {} ).collect(&:id) & allowed_ids
=> [1830, 1831, 1826, 1832, 1825, 1833, 1834, 1827, 1689, 1680, 1688, 1679,
1686, 1684, 1676, 1858, 1859, 1860, 1861, 1865, 1236]

OK - looks good.  But, when i try to paginate into some actual pages, the
order breaks:  first, without AR conditions:
>> ActsAsFerret::find("rhythm", [TeachingObject],{ :page =>
1, :per_page =>
10 }, {} ).collect(&:id)
=> [4038, 698, 4039, 1830, 1831, 1826, 1832, 1825, 1833, 411]

That all seems to be in order - i get the first ten results from the big
list, above.

Now, if we were to apply the allowed_ids condition here, we''d expect
the
results to start
[1830, 1831, 1826, 1832, 1825, 1833, ...] - right?  Because we should have
the same ordering applied to the remaining resources, and then we get the
first ten for page 1.  But, the ordering is different -
>> ActsAsFerret::find("rhythm", [TeachingObject],{ :page =>
1, :per_page =>
10 }, {:conditions => ["id in (?)", allowed_ids] }
).collect(&:id)
=> [1826, 1825, 1689, 1680, 1688, 1679, 1686, 1684, 1676, 1236]

So, it seems that pagination + ferret score ordering + AR conditions is a
bad combination

Again, sorry to not supply test cases but we don''t use them (i know, i
know!!!).  Can anyone shed any light?

thanks - max

2008/7/9 Jens Kraemer <jk at jkraemer.net>:
> Hi folks,
>
> On 09.07.2008, at 06:01, Jeff Webb wrote:
>
>> Sheldon/Jens,
>>
>> Any chance that this has been figured out and patched?
>>
>
> I just committed a fix to this problem to trunk, so pagination with sorting
> and AR conditions should work now.
>
>
> cheers,
> Jens
>
> --
> Jens Kr?mer
> http://www.jkraemer.net/ - Blog
> http://www.omdb.org/     - The new free film database
>
>
>
>
>
>
>
>
> _______________________________________________
> Ferret-talk mailing list
> Ferret-talk at rubyforge.org
> http://rubyforge.org/mailman/listinfo/ferret-talk
>
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Max,

Here is what I changed in the current stable version of AAF in my local
plugin install to get conditions and pagination working. I have not fully
tested it except for my particular use cases but it seems to work out.
Sorting is not factored into these changes.

Basically if there is no pagination OR no AR conditions you can let ferret
do all the work for you. If you have both of these then you need to return
all results, merge with ferret IDs, then do your offset and limit. I
replicated what Jens has done on the AAF trunk.

Hope this works for you. I have not heard if Jens is going to add this to
the current branch as a hotfix.

replace the existing ar_by_contents method in class_methods.rb with:

####################################
#changes to ar_find_by_contents AAF 0.4.3#
####################################

    def ar_find_by_contents(q, options = {}, find_options = {})
      result_ids = {}
      has_conditions = !find_options[:conditions].blank? || caller.find{
|call| call =~ %r{active_record/associations} }

      # odd case - cannot do pagination combo with AR & Ferret
      # must retrieve all then paginate after
      if options[:per_page] && has_conditions
        late_paginate = true
        offset  = find_options.delete(:offset)
        limit   = find_options.delete(:limit)
        options.delete(:page)
        options.delete(:per_page)
        find_options.delete(:offset)
        find_options.delete(:limit)
        options[:limit] = :all
      end

      total_hits = find_id_by_contents(q, options) do |model, id, score,
data|
        # stores ids, index and score of each hit for later ordering of
        # results
        result_ids[id] = [ result_ids.size + 1, score ]
      end

      result = retrieve_records( { self.name => result_ids }, find_options )

      if has_conditions
        # what we got from the database is our full result set, so take
it''s
size
        total_hits = result.length

        if late_paginate
          result = result[offset..offset+limit-1]
        end
      end

      [ total_hits, result ]
    end


Jeff



On Fri, Jul 18, 2008 at 4:11 AM, Max Williams <toastkid.williams at
gmail.com>
wrote:
> Hi Jens/all
>
> I''ve been playing with latest version, and it seems that the
combination of
> AR conditions, paginating and AR order (eg ":order =>
"name") seems to be
> fine now, even on our server, which was were it was broken before (it
always
> worked locally, weirdly).
>
> However, i''ve just tried it with results that are sorted by ferret
on the
> basis of their boost score, and it seems broken.
>
> I''m sorry i don''t have any tests set up but if i walk
through an example
> can anyone see something that maybe i''m doing wrong?  Or shed any
light?
>
> I use AR conditions to filter the results through a set of ids that an
> individual user is allowed to view.  I just have a method User#allowed_ids
> for this that returns an array of integers.  For the purpose of
> illustration, though, let''s say that the allowed ids are
everything between
> 1000 & 2000.
> allowed_ids = (1000..2000).to_a
> => [1000, 1001, 1002, etc, 2000]
>
> For a particular search (on ''rhythm'') i get these results
back - the order
> is the order calculated by ferret/aaf on the basis of boost values:
i''ve
> collected them by id for clarity.  In this example i''ve set a big
per_page
> to get all the results.
>
> >> ActsAsFerret::find("rhythm", [TeachingObject],{ :page
=> 1, :per_page =>
> 1000 }, {} ).collect(&:id)
> => [4038, 698, 4039, 1830, 1831, 1826, 1832, 1825, 1833, 411, 1834, 702,
> 1827, 1689, 1680, 1688, 1679, 1686, 1684, 1676, 2129, 2130, 2131, 1858,
> 1859, 1860, 1861, 1865, 2132, 2141, 2345, 2350, 2352, 2353, 2356, 2360,
> 2362, 2366, 2368, 2371, 2372, 2373, 2376, 2377, 2378, 2384, 2385, 2389,
> 2407, 2414, 2417, 2419, 2427, 2428, 2438, 2439, 2458, 2459, 2473, 2474,
> 2475, 2477, 2478, 2133, 2349, 2361, 2363, 2365, 2370, 2375, 2383, 2386,
> 2392, 2415, 2430, 2431, 2440, 2441, 2442, 2472, 2142, 3751, 2161, 1236]
>
> Now, when i apply the condition of only being in the allowed ids,
i''d
> expect the remaining ids to be in the same order as above, and that is in
> fact the case:
>
> >> ActsAsFerret::find("rhythm", [TeachingObject],{ :page
=> 1, :per_page =>
> 1000 }, {:conditions => ["id in (?)", allowed_ids] }
).collect(&:id)
> => [1830, 1831, 1826, 1832, 1825, 1833, 1834, 1827, 1689, 1680, 1688,
1679,
> 1686, 1684, 1676, 1858, 1859, 1860, 1861, 1865, 1236]
>
> Just to check, let''s do the original again (with no AR conditions)
and just
> do set intersection with the allowed_ids
> >> ActsAsFerret::find("rhythm", [TeachingObject],{ :page
=> 1, :per_page =>
> 1000 }, {} ).collect(&:id) & allowed_ids
> => [1830, 1831, 1826, 1832, 1825, 1833, 1834, 1827, 1689, 1680, 1688,
1679,
> 1686, 1684, 1676, 1858, 1859, 1860, 1861, 1865, 1236]
>
> OK - looks good.  But, when i try to paginate into some actual pages, the
> order breaks:  first, without AR conditions:
>
> >> ActsAsFerret::find("rhythm", [TeachingObject],{ :page
=> 1, :per_page =>
> 10 }, {} ).collect(&:id)
> => [4038, 698, 4039, 1830, 1831, 1826, 1832, 1825, 1833, 411]
>
> That all seems to be in order - i get the first ten results from the big
> list, above.
>
> Now, if we were to apply the allowed_ids condition here, we''d
expect the
> results to start
> [1830, 1831, 1826, 1832, 1825, 1833, ...] - right?  Because we should have
> the same ordering applied to the remaining resources, and then we get the
> first ten for page 1.  But, the ordering is different -
>
> >> ActsAsFerret::find("rhythm", [TeachingObject],{ :page
=> 1, :per_page =>
> 10 }, {:conditions => ["id in (?)", allowed_ids] }
).collect(&:id)
> => [1826, 1825, 1689, 1680, 1688, 1679, 1686, 1684, 1676, 1236]
>
> So, it seems that pagination + ferret score ordering + AR conditions is a
> bad combination
>
> Again, sorry to not supply test cases but we don''t use them (i
know, i
> know!!!).  Can anyone shed any light?
>
> thanks - max
>
> 2008/7/9 Jens Kraemer <jk at jkraemer.net>:
>
> Hi folks,
>>
>> On 09.07.2008, at 06:01, Jeff Webb wrote:
>>
>>> Sheldon/Jens,
>>>
>>> Any chance that this has been figured out and patched?
>>>
>>
>> I just committed a fix to this problem to trunk, so pagination with
>> sorting and AR conditions should work now.
>>
>>
>> cheers,
>> Jens
>>
>> --
>> Jens Kr?mer
>> http://www.jkraemer.net/ - Blog
>> http://www.omdb.org/     - The new free film database
>>
>>
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>> Ferret-talk mailing list
>> Ferret-talk at rubyforge.org
>> http://rubyforge.org/mailman/listinfo/ferret-talk
>>
>
>
> _______________________________________________
> Ferret-talk mailing list
> Ferret-talk at rubyforge.org
> http://rubyforge.org/mailman/listinfo/ferret-talk
>


-- 

Jeff Webb
jeff at boowebb.com
http://boowebb.com/
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Hi Jeff - thanks a lot for looking at this.

I discovered that since last august, will paginate lets you paginate any
arbitrary array - so you can paginate an existing set of results.  so what
i''m doing now is this
- get the results using ferret find, passing through the AR conditions and a
large per page which means there''s no pagination, effectively.  The
sorting
(by ferret score) is correct.
- cache the results with memcache, using params (minus the page k-v pair) as
a cache key - this means that the retrieve will be slow the first time but
very quick if the user just wants to look at another page
- then paginate the results, simply doing "@all_results.paginate(:page
=>
params[:page], :per_page => 20)"

This is pretty similar to your patch i think - get results with ferret and
then paginate - and it''s working fine for me.  The size of my result
set
returned by ferret is rarely more than 150 big, so getting all results
isn''t
a problem.  Obviously it''s not very scaleable though.

thanks!
max

2008/7/18 Jeff Webb <jeff at boowebb.com>:
> Max,
>
> Here is what I changed in the current stable version of AAF in my local
> plugin install to get conditions and pagination working. I have not fully
> tested it except for my particular use cases but it seems to work out.
> Sorting is not factored into these changes.
>
> Basically if there is no pagination OR no AR conditions you can let ferret
> do all the work for you. If you have both of these then you need to return
> all results, merge with ferret IDs, then do your offset and limit. I
> replicated what Jens has done on the AAF trunk.
>
> Hope this works for you. I have not heard if Jens is going to add this to
> the current branch as a hotfix.
>
> replace the existing ar_by_contents method in class_methods.rb with:
>
> ####################################
> #changes to ar_find_by_contents AAF 0.4.3#
> ####################################
>
>     def ar_find_by_contents(q, options = {}, find_options = {})
>       result_ids = {}
>       has_conditions = !find_options[:conditions].blank? || caller.find{
> |call| call =~ %r{active_record/associations} }
>
>       # odd case - cannot do pagination combo with AR & Ferret
>       # must retrieve all then paginate after
>       if options[:per_page] && has_conditions
>         late_paginate = true
>         offset  = find_options.delete(:offset)
>         limit   = find_options.delete(:limit)
>         options.delete(:page)
>         options.delete(:per_page)
>         find_options.delete(:offset)
>         find_options.delete(:limit)
>         options[:limit] = :all
>       end
>
>       total_hits = find_id_by_contents(q, options) do |model, id, score,
> data|
>         # stores ids, index and score of each hit for later ordering of
>         # results
>         result_ids[id] = [ result_ids.size + 1, score ]
>       end
>
>       result = retrieve_records( { self.name => result_ids },
find_options
> )
>
>       if has_conditions
>         # what we got from the database is our full result set, so take
> it''s size
>         total_hits = result.length
>
>         if late_paginate
>           result = result[offset..offset+limit-1]
>         end
>       end
>
>       [ total_hits, result ]
>     end
>
>
> Jeff
>
>
>
>
> On Fri, Jul 18, 2008 at 4:11 AM, Max Williams <toastkid.williams at
gmail.com>
> wrote:
>
>> Hi Jens/all
>>
>> I''ve been playing with latest version, and it seems that the
combination
>> of AR conditions, paginating and AR order (eg ":order =>
"name") seems to be
>> fine now, even on our server, which was were it was broken before (it
always
>> worked locally, weirdly).
>>
>> However, i''ve just tried it with results that are sorted by
ferret on the
>> basis of their boost score, and it seems broken.
>>
>> I''m sorry i don''t have any tests set up but if i walk
through an example
>> can anyone see something that maybe i''m doing wrong?  Or shed
any light?
>>
>> I use AR conditions to filter the results through a set of ids that an
>> individual user is allowed to view.  I just have a method
User#allowed_ids
>> for this that returns an array of integers.  For the purpose of
>> illustration, though, let''s say that the allowed ids are
everything between
>> 1000 & 2000.
>> allowed_ids = (1000..2000).to_a
>> => [1000, 1001, 1002, etc, 2000]
>>
>> For a particular search (on ''rhythm'') i get these
results back - the order
>> is the order calculated by ferret/aaf on the basis of boost values:
i''ve
>> collected them by id for clarity.  In this example i''ve set a
big per_page
>> to get all the results.
>>
>> >> ActsAsFerret::find("rhythm", [TeachingObject],{
:page => 1, :per_page
>> => 1000 }, {} ).collect(&:id)
>> => [4038, 698, 4039, 1830, 1831, 1826, 1832, 1825, 1833, 411, 1834,
702,
>> 1827, 1689, 1680, 1688, 1679, 1686, 1684, 1676, 2129, 2130, 2131, 1858,
>> 1859, 1860, 1861, 1865, 2132, 2141, 2345, 2350, 2352, 2353, 2356, 2360,
>> 2362, 2366, 2368, 2371, 2372, 2373, 2376, 2377, 2378, 2384, 2385, 2389,
>> 2407, 2414, 2417, 2419, 2427, 2428, 2438, 2439, 2458, 2459, 2473, 2474,
>> 2475, 2477, 2478, 2133, 2349, 2361, 2363, 2365, 2370, 2375, 2383, 2386,
>> 2392, 2415, 2430, 2431, 2440, 2441, 2442, 2472, 2142, 3751, 2161, 1236]
>>
>> Now, when i apply the condition of only being in the allowed ids,
i''d
>> expect the remaining ids to be in the same order as above, and that is
in
>> fact the case:
>>
>> >> ActsAsFerret::find("rhythm", [TeachingObject],{
:page => 1, :per_page
>> => 1000 }, {:conditions => ["id in (?)", allowed_ids] }
).collect(&:id)
>> => [1830, 1831, 1826, 1832, 1825, 1833, 1834, 1827, 1689, 1680,
1688,
>> 1679, 1686, 1684, 1676, 1858, 1859, 1860, 1861, 1865, 1236]
>>
>> Just to check, let''s do the original again (with no AR
conditions) and
>> just do set intersection with the allowed_ids
>> >> ActsAsFerret::find("rhythm", [TeachingObject],{
:page => 1, :per_page
>> => 1000 }, {} ).collect(&:id) & allowed_ids
>> => [1830, 1831, 1826, 1832, 1825, 1833, 1834, 1827, 1689, 1680,
1688,
>> 1679, 1686, 1684, 1676, 1858, 1859, 1860, 1861, 1865, 1236]
>>
>> OK - looks good.  But, when i try to paginate into some actual pages,
the
>> order breaks:  first, without AR conditions:
>>
>> >> ActsAsFerret::find("rhythm", [TeachingObject],{
:page => 1, :per_page
>> => 10 }, {} ).collect(&:id)
>> => [4038, 698, 4039, 1830, 1831, 1826, 1832, 1825, 1833, 411]
>>
>> That all seems to be in order - i get the first ten results from the
big
>> list, above.
>>
>> Now, if we were to apply the allowed_ids condition here, we''d
expect the
>> results to start
>> [1830, 1831, 1826, 1832, 1825, 1833, ...] - right?  Because we should
have
>> the same ordering applied to the remaining resources, and then we get
the
>> first ten for page 1.  But, the ordering is different -
>>
>> >> ActsAsFerret::find("rhythm", [TeachingObject],{
:page => 1, :per_page
>> => 10 }, {:conditions => ["id in (?)", allowed_ids] }
).collect(&:id)
>> => [1826, 1825, 1689, 1680, 1688, 1679, 1686, 1684, 1676, 1236]
>>
>> So, it seems that pagination + ferret score ordering + AR conditions is
a
>> bad combination
>>
>> Again, sorry to not supply test cases but we don''t use them (i
know, i
>> know!!!).  Can anyone shed any light?
>>
>> thanks - max
>>
>> 2008/7/9 Jens Kraemer <jk at jkraemer.net>:
>>
>> Hi folks,
>>>
>>> On 09.07.2008, at 06:01, Jeff Webb wrote:
>>>
>>>> Sheldon/Jens,
>>>>
>>>> Any chance that this has been figured out and patched?
>>>>
>>>
>>> I just committed a fix to this problem to trunk, so pagination with
>>> sorting and AR conditions should work now.
>>>
>>>
>>> cheers,
>>> Jens
>>>
>>> --
>>> Jens Kr?mer
>>> http://www.jkraemer.net/ - Blog
>>> http://www.omdb.org/     - The new free film database
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> Ferret-talk mailing list
>>> Ferret-talk at rubyforge.org
>>> http://rubyforge.org/mailman/listinfo/ferret-talk
>>>
>>
>>
>> _______________________________________________
>> Ferret-talk mailing list
>> Ferret-talk at rubyforge.org
>> http://rubyforge.org/mailman/listinfo/ferret-talk
>>
>
>
>
> --
>
> Jeff Webb
> jeff at boowebb.com
> http://boowebb.com/
>
> _______________________________________________
> Ferret-talk mailing list
> Ferret-talk at rubyforge.org
> http://rubyforge.org/mailman/listinfo/ferret-talk
>
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