We are upgrading to Solr 4.8 from 3.5, and I was testing search results with
4.8. I found that with an edismax request handler the pf param is being
treated differently.
In 3.5 it was used as a disjunction max with tiebreaker, i.e. the max score
from all the matching fields was taken and the tiebreaker*sum of other
fields was added to it. In 4.8 it just adds all the match scores together
(from all the fields). This is throwing some scores off quite a bit from
3.5. The configuration for the handler is the same.
I couldn't find any mention of this change searching online, or any mention
of pf being treated differently than qf. What changed in Solr 4 that caused
this? Is there any way I can get the old behavior, of taking the max field
score plus the tie-breaker times the sum of the other field scores? Maybe a
simple change to the format of my request handler:
More details:
Turning debug query on, the results are the following, They clearly show
that that max is used with the tiebreaker in 3.5 but not 4.8 for pf:
query (3.5):
boost(+(((inlink_text:edg^1.2 | body:edg^0.5 | title:edg^1.2 |
meta_description:edg^0.5 | url_path:edg^1.2 | file_name:edg^1.2 |
primary_header:edg^1.2 | secondary_header:edg^0.5)~0.17
(inlink_text:detect^1.2 | body:detect^0.5 | title:detect^1.2 |
meta_description:detect^0.5 | url_path:detect^1.2 | file_name:detect^1.2 |
primary_header:detect^1.2 | secondary_header:detect^0.5)~0.17)~2)*
(inlink_text:"edg detect"~100^1.2 | body:"edg detect"~100^0.5 | title:"edg
detect"~100^1.2 | meta_description:"edg detect"~100^0.5 | url_path:"edg
detect"~100^1.2 | file_name:"edg detect"~100^1.2 | primary_header:"edg
detect"~100^1.2 | secondary_header:"edg
detect"~100^0.5)~0.17*,product(float(hier_score),pow(float(link_score),const(0.25))))
pf results for one (3.5):
<lst>
<bool name="match">true</bool>
<float name="value">1.5689207</float>
<str name="description">max plus 0.17 times others of:</str>
<arr name="details">
<lst>
<bool name="match">true</bool>
<float name="value">1.5596248</float>
<str name="description">...</str>
<arr name="details">...</arr>
</lst>
<lst>
<bool name="match">true</bool>
<float name="value">0.054681662</float>
<str name="description">...</str>
<arr name="details">...</arr>
</lst>
</arr>
However, in 4.8, "max" and the tie-breaker are nowhere to be seen for the pf
part of the query:
query (4.8):
boost(+(((inlink_text:edg^1.2 | body:edg^0.5 | title:edg^1.2 |
meta_description:edg^0.5 | url_path:edg^1.2 | file_name:edg^1.2 |
primary_header:edg^1.2 | secondary_header:edg^0.5)~0.17
(inlink_text:detect^1.2 | body:detect^0.5 | title:detect^1.2 |
meta_description:detect^0.5 | url_path:detect^1.2 | file_name:detect^1.2 |
primary_header:detect^1.2 | secondary_header:detect^0.5)~0.17)~2)* body:"edg
detect"~100^0.5 title:"edg detect"~100^1.2 url_path:"edg detect"~100^1.2
file_name:"edg detect"~100^1.2 primary_header:"edg detect"~100^1.2
secondary_header:"edg detect"~100^0.5 meta_description:"edg detect"~100^0.5
inlink_text:"edg
detect"~100^1.2*,product(float(hier_score),pow(float(link_score),const(0.25))))
pf results for one (4.8) (no max, both values are just listed under the "sum
of" element:
<lst>
<bool name="match">true</bool>
<float name="value">0.03554287</float>
<str name="description">...</str>
<arr name="details">...</arr>
</lst>
<lst>
<bool name="match">true</bool>
<float name="value">1.0933692</float>
<str name="description">...</str>
<arr name="details">...</arr>
</lst>
The Solr 4 handler used is the following - it's also the same as the 3.5
one:
<requestHandler class="solr.SearchHandler" name="/sitewide">
<lst name="defaults">
<str name="defType">edismax</str>
<str name="echoParams">explicit</str>
<float name="tie">0.17</float>
<str name="qf">
body^0.5 title^1.2 url_path^1.2 file_name^1.2 primary_header^1.2
secondary_header^0.5 meta_description^0.5 inlink_text^1.2
</str>
<str name="pf">
body^0.5 title^1.2 url_path^1.2 file_name^1.2 primary_header^1.2
secondary_header^0.5 meta_description^0.5 inlink_text^1.2
</str>
<int name="ps">100</int>
<str name="boost">
hier_score
</str>
<str name="boost">
pow(link_score,0.25)
</str>
</lst>
<lst name="spellchecker">
<str name="spellcheck.onlyMorePopular">false</str>
<str name="spellcheck.extendedResults">true</str>
<str name="spellcheck.count">3</str>
<str name="buildOnCommit">true</str>
</lst>
<arr name="last-components">
<str>spellcheck</str>
</arr>
</requestHandler>
--
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