Hi,
I'm developping an image database. Each lucene document
representing an image contains (among other fields ):
- a date field
- a collection field containing the ID of the collection the
image
belongs to.
I want to be able to give a score to each collection. Collections
with a higher score appear first in the results. I want to avoid
re-indexing all the documents each time i change my collection
scores.
For example on day 1 I decide to give collection #1 a 5 score and
collection #3 a 10 score --> images belonging to collection #3 appear
first in search results.
One day 2 i give collection #3 a 2 score --> images belonging to
collection #1 appear first in search results.
I have read the lucene docs, and from what i understand there are
many ways to achieve what I want :
- I can use a Very big Boolean query (OR query in fact)
containing
one TermQuery per collection ID, setting the correct boost factor for
each termquery. The problem with this is that i have 300 collections,
so i have a boolean query with 300 terms that i append to each
query i
make. I am afraid that it will be slow.
- I can use a ValueSourceQuery, where for each document i compute
a custom score based on the value of the collection field. Will it be
faster than the first solution?
- I can do advanced things such as writing a custom HitCollector,
or a custom Query.
- I can add another field to each document, containing a computed
custom score, then i could sort on that field. But i want to avoid
this solution at all costs, since it would mean re-indexing all the
documents each time the collection scores change.
What solution do you suggest? Is there another solution that i
didnt mention?
More recent documents should also come first : In fact the final
sorting should be a ponderated sum between the collection score of an
image and the date of an image : most recent images from the
best-scored collections come first, then most recent from less-
scrored
collections, then less recent from best scored, and so on. I would
also like to be able to adjust the balance between date/collection
score.
What solution do you suggest?
I would also like to implement random-sorting. My solution is : i
create 12 new fields R1 -> R12 for each document, each containing a
random number between 1 and 12. To get a random sort, i sort each day
with a different combination of R1 .. R12. For example :
Day 1 : i sort by R1 then R4 then R5..
Day 2 : i sort by R10 then R9 then R2....
etc...
Is it a good solution? Is there another way to do it?
Very big thx in advance for your answers.
Antoine
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