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From Federico Pici <>
Subject Re: About custom score using Solr8/Lucene8
Date Thu, 09 May 2019 10:07:17 GMT

my index is basically a list of documents of users. so i could say i got a couple of millions
of documents per user.

I need to produce a score that is unrelated with search term (something like “give me documents
that are the most important to user”). I would 
search for documents of a user without specifying a particular term. Documents that are the
most important for a user are calculated with strategy based 
on particular text analysis (we still do not have a strategy).

I evaluated the idea of storing a score for each document based on an external scoring strategy
(a job that reindex each user’s document every night?), but 
i do not know how could scale up (more user with many documents could make this strategy problematic
in the long time), so the idea was to be able
to calculate this scoring (or other scoring strategy) trying to follow some best-practice
(and as i can see using CustomScoreQuery is the most preferred way)

I was not able to try a solution because of Lucene8 missing CustomScoreQuery.
I made something very basic using ValueSourceParser (but is this a good practice?)

> Il giorno 9 mag 2019, alle ore 10:50, Diego Ceccarelli (BLOOMBERG/ LONDON) <>
ha scritto:
> Hi Federico, 
> Could you give more details on what is the score that you want to produce? how big is
the collection? 
> Is the score affected by the query? if not, would be possible to store the score with
the document? 
> Cheers,
> Diego
> From: At: 05/09/19 08:13:35To:
> Subject: Re: About custom score using Solr8/Lucene8
> Hello Mikhail,
> yes i did. I read all the page at 
> <>
> I still do not understand where/how to start to write a class to be embedded in 
> solr8. All
> available example since 2012 where written around 
> CustomScoreQuery/CustomScoreProvider.
> I really don’t know how to setup a minimal project to implement custom scoring 
> in solr8/lucene8 using FunctionScoreQuery
>> Il giorno 8 mag 2019, alle ore 22:15, Mikhail Khludnev <> ha

> scritto:
>> Hello.
>> Have you checked the fourth item at
>> ?
>> On Wed, May 8, 2019 at 5:46 PM Federico Pici <>
>> wrote:
>>> Hi,
>>> i was trying to implement custom score inside my solr8 instance.
>>> On google i found some examples, all focused on using CustomScoreProvider
>>> and CustomScoreQuery classes. This classes have been removed in
>>> Solr8/Lucene8
>>> and, from Lucene 8 changeling, i saw a developer /contributor saying to
>>> use FunctionScoreQuery.
>>> Googling around was unsuccessful as i found no example, so i have no clue
>>> from where to start from
>>> I think i have a very basic need. Generate a score from field in
>>> documents using logic completely unrelated with query itself.
>>> The only way available (until any clue…) is using
>>> Is there any example, at least to understand how to start a minimal basic
>>> project?
>>> Thanks
>>> ---------------------------------------------------------------------
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>> -- 
>> Sincerely yours
>> Mikhail Khludnev

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