Hello!
I am using the multi_match's cross_field
<http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/query-dsl-multi-match-query.html#type-cross-fields>
query.
It works very well and is exactly what I need. However, in some rare
circumstances the order of the results doesn't match my expectations. It
turns out that the scoring of the first results is much higher than the
score of the rest of the documents. I had a closer look at the explain
statements and was surprised by the way the scores were calculated:
for the first doc:
{
"value": 8.252264,
"description": "fieldWeight in 998806, product of:",
"details": [
{
"value": 1,
"description": "tf(freq=1.0), with freq of:",
"details": [
{
"value": 1,
"description": "termFreq=1.0"
}
]
},
{
"value": 8.252264,
"description": "idf(docFreq=13182, maxDocs=18605118)"
},
{
"value": 1,
"description": "fieldNorm(doc=998806)"
}
]
}
and for the doc that is supposed to be first:
{
"value": 3.8485851,
"description": "score(doc=700068,freq=1.0 = termFreq=1.0\n), product
of:",
"details": [
{
"value": 0.46578622,
"description": "queryWeight, product of:",
"details": [
{
"value": 18,
"description": "boost"
},
{
"value": 8.262557,
"description": "idf(docFreq=13047, maxDocs=18605118)"
},
{
"value": 0.0031318406,
"description": "queryNorm"
}
]
},
{
"value": 8.262557,
"description": "fieldWeight in 700068, product of:",
"details": [
{
"value": 1,
"description": "tf(freq=1.0), with freq of:",
"details": [
{
"value": 1,
"description": "termFreq=1.0"
}
]
},
{
"value": 8.262557,
"description": "idf(docFreq=13047, maxDocs=18605118)"
},
{
"value": 1,
"description": "fieldNorm(doc=700068)"
}
]
}
]
}
You can see that the queryWeight factor is missing in the calculation of
the first doc, which leads to a much higher total score. I am no expert in
it, but this seems to be a bug in my eyes. Or did I misunderstand something?
You can find the query and the result list here:
https://gist.github.com/christophlingg/0014ba3d6d334a27cccd
Thanks for your help!
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