FAQ
Instead of using a function query, could I use the edismax query (plus some
low cost filters not shown in the example) and implement the
scale/sum/product computation in a PostFilter? Is the query's maxScore
available there?

Thanks,
Peter

On Wed, Nov 27, 2013 at 1:58 PM, Peter Keegan wrote:

Although the 'scale' is a big part of it, here's a closer breakdown. Here
are 4 queries with increasing functions, and theei response times (caching
turned off in solrconfig):

100 msec:
select?q={!edismax v='news' qf='title^2 body'}

135 msec:
select?qq={!edismax v='news' qf='title^2
body'}q={!func}product(field(myfield),query($qq)&fq={!query v=$qq}

200 msec:
select?qq={!edismax v='news' qf='title^2
body'}q={!func}sum(product(0.75,query($qq)),product(0.25,field(myfield))))&fq={!query
v=$qq}

320 msec:
select?qq={!edismax v='news' qf='title^2
body'}&scaledQ=scale(product(query($qq),1),0,1)&q={!func}sum(product(0.75,$scaledQ),product(0.25,field(myfield)))&fq={!query
v=$qq}

Btw, that no-op product is necessary, else you get this exception:

org.apache.lucene.search.BooleanQuery$BooleanWeight cannot be cast to org.apache.lucene.queries.function.valuesource.ScaleFloatFunction$ScaleInfo

thanks,

peter



On Wed, Nov 27, 2013 at 1:30 PM, Chris Hostetter <hossman_lucene@fucit.org
wrote:
: So, this query does just what I want, but it's typically 3 times slower
: than the edismax query without the functions:

that's because the scale() function is inhernetly slow (it has to
compute the min & max value for every document in order to know how to
scale them)

what you are seeing is the price you have to pay to get that query with a
"normalized" 0-1 value.

(you might be able to save a little bit of time by eliminating that
no-Op multiply by 1: "product(query($qq),1)" ... but i doubt you'll even
notice much of a chnage given that scale function.

: Is there any way to speed this up? Would writing a custom function query
: that compiled all the function queries together be any faster?

If you can find a faster implementation for scale() then by all means let
us konw, and we can fold it back into Solr.


-Hoss

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