You are right with function score query. This is surely the most powerful
way to manipulate scores the way you like to do.
Jörg
On Tue, Mar 3, 2015 at 2:26 AM, Joel Potischman <
joel.potisch...@beatport.com> wrote:
> Thanks Jörg, that makes sense.
>
> I've made that change and it works but I'm still struggling to have
> scoring behave the way I want. I simplified the query in my original post
> for clarity. The actual query, with the new flag, is more like this:
>
> {
> "query": {
> "bool": {
> "should": [
> {
> "match": {
> "display_name.raw": {
> "query": "{{q}}",
> "type": "phrase"
> }
> }
> },
> {
> "match": {
> "display_name.raw_folded": {
> "boost": 5,
> "query": "{{q}}",
> "type": "phrase"
> }
> }
> },
> {
> "bool": {
> "must_not": {
> "term": {
> "some_flag": true
> }
> },
> "boost": 0.00001
> }
> }
> ]
> }
> }
> }
>
> I have the *display_name* field indexed two additional ways - "raw" and
> "raw_folded", "raw" is an exact phrase match, and "raw_folded" is the same
> thing with accents/diacritics stripped, so if a query matches raw_folded,
> it will always match raw as well and score higher.
>
> I want to use this new clause on *some_flag* to only *slightly* decrease
> scoring, but due to normalizing I'm finding it very different to do so
> without wildly swinging the scores of other records due to boost
> normalization. I'd ideally want the presence of this flag set to true to
> reduce score by say 1%. The exact number is not important, I just want to
> make sure that when multiple records match, those with this flag set to
> true rank slightly lower. Think of it as a tiebreaker flag.
>
> I know about function_score queries but that would be a major risk to
> implement now, as a) I believe it would require a substantial rewrite of my
> template, and b) I've never used them before, and c) we are going live very
> soon. If that's really the right way to do this I'll ticket it for after
> launch, but I'm hopeful there's a way to do this that only involves minor
> tweaks to our existing templates. Any (additional!) guidance is very much
> appreciated!
>
> -joel
>
> On Monday, March 2, 2015 at 1:25:49 PM UTC-5, Jörg Prante wrote:
>>
>> Negative boosts are not supported. The challenge in downranking is that
>> each boost value will contribute to the score and push docs higher, also
>> when using very small boost values or negative values. This is not what is
>> expected.
>>
>> The trick for successful downranking is to reward all docs that do not
>> match the condition
>>
>> {
>> "bool": {
>> "must_not": {
>> "term": {
>> "some_flag": true
>> }
>> },
>> "boost": 0.00001
>> }
>> }
>>
>> which is equivalent to
>>
>> {
>> "bool": {
>> "must": {
>> "term": {
>> "some_flag": false
>> }
>> },
>> "boost": 0.00001
>> }
>> }
>>
>> given that some_flag exists in all docs.
>>
>> This clause means: reward all docs that do not match the condition
>> some_flag=true and push them higher in the result set. In other words,
>> penalize all docs that match the condition some_flag=true.
>>
>> Jörg
>>
>>
>>
>> On Mon, Mar 2, 2015 at 7:03 PM, Joel Potischman <joel.po...@beatport.com>
>> wrote:
>>
>>> I have a query template that currently returns results exactly as
>>> desired. I've been given a requirement to very slightly downrank results
>>> that have an optional boolean field set to True. The intent is to ensure
>>> that we return everything that matches the query, but if multiple records
>>> match, any with this flag set to true come up later in results. In case
>>> it's relevant, most records will not contain this flag. I came up with the
>>> following (simplified) version of my query which works great:
>>>
>>> {
>>> "query": {
>>> "bool": {
>>> "should": [
>>> {
>>> "match": {
>>> "my_field": {
>>> "query": "{{q}}"
>>> }
>>> }
>>> },
>>> {
>>> "bool": {
>>> "must": {
>>> "term": {
>>> "some_flag": true
>>> }
>>> },
>>> "boost": -0.00001
>>> }
>>> }
>>> ]
>>> }
>>> }
>>> }
>>>
>>> A colleague said that we learned in our Elasticsearch training last year
>>> that we should avoid negative boosts, and I should rewrite the second
>>> clause as follows
>>>
>>> {
>>> "bool": {
>>> "must_not": {
>>> "term": {
>>> "some_flag": false
>>> }
>>> },
>>> "boost": 0.00001
>>> }
>>> }
>>>
>>> I don't recall learning that, and this construction strikes me as less
>>> performant, as it must modify most records instead of just the minority
>>> that will have *some_flag=true*.
>>>
>>> Because we're both relatively new to Elasticsearch we'd very much
>>> appreciate someone with more experience to weigh in. I'm happy to change it
>>> if it's the right thing to do. I'm just not sure I believe it is, and if
>>> so, why.
>>>
>>> Thanks in advance.
>>>
>>> -joel
>>>
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>>
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