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From Ken Krugler <>
Subject Re: Boolean query with 50,000 clauses! Possible? Scalable?
Date Sun, 26 Jul 2009 21:18:14 GMT
>awarnier wrote:
>>  Edoardo Marcora wrote:
>>>  I am faced with the requirement for a boolean query composed of 50,000
>>>  clauses (all of them directed at the same field) all OR'ed together.
>>  By pure intellectual curiosity : can you provide some idea of the type
>>  of query, and the type of content of the field this is targeted at ?
>>  I have this notion that with 50,000 queries directed at one field, there
>>  must be some smarter way of handling this than just OR-ing together the
>>  results.
>What I would like to do is to take the results of one query and use one of
>its fields (not the docid) as an argument to another query (much like a
>subquery in SQL). For example:
>type:foo AND (_query_:type:bar AND field2:{field1})
>This should search for all types of foo and then iterate over the result set
>and perform a query for where type is bar and field2 is equal to the value
>of field1 from each item of the first result set.

This looks like a more like this (MLT) query, where you restrict the 
set to documents that have matching types...though I don't understand 
the type:foo AND type:bar query, unless 'type' is a multi-value field.

 From what I remember of using MLT support in Lucene a few years back, 
this takes the terms of the target field from the target document, 
tosses out stop words, and then uses some arbitrary limit (e.g. 500) 
for the first N terms used to do the query.

Unless the distribution of terms in the field is heavily skewed, this 
gives you pretty good results. I supposed you could use the N most 
common terms - but your stop word list isn't good, you'll get worse 

In any case, preprocessing the field will speed things up, versus 
doing any analysis/stop word/frequency calculations at query time.

-- Ken
Ken Krugler
+1 530-265-2225
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