Well, I fixed my own problem in the end. For the record, this is the
schema I ended up going with:
<fieldType name="text_bigram" class="solr.TextField" omitNorms="true">
<analyzer>
<tokenizer class="solr.WhitespaceTokenizerFactory" />
<filter class="solr.LowerCaseFilterFactory" />
<filter class="solr.NGramFilterFactory" maxGramSize="2"
minGramSize="2" />
</analyzer>
<analyzer type="query">
<tokenizer class="solr.WhitespaceTokenizerFactory" />
<filter class="solr.LowerCaseFilterFactory" />
<filter class="solr.NGramFilterFactory" maxGramSize="2"
minGramSize="2"/>
</analyzer>
</fieldType>
I could have left it a trigram but went with a bigram because with this
setup, I can get queries to properly hit as long as the min/max gram
size is met. In other words, for any queries two or more characters
long, this works for me. Less than two characters and it fails.
I don't know exactly why that is, but I'll take it anyway!
- Charlie
-----Original Message-----
From: Charlie Jackson [mailto:charlie.jack...@cision.com]
Sent: Friday, October 23, 2009 10:00 AM
To: solr-user@lucene.apache.org
Subject: NGram query failing
I have a requirement to be able to find hits within words in a free-form
id field. The field can have any type of alphanumeric data - it's as
likely it will be something like "123456" as it is to be "SUN-123-ABC".
I thought of using NGrams to accomplish the task, but I'm having a
problem. I set up a field like this
<fieldType name="text_trigram" class="solr.TextField"
positionIncrementGap="100">
<analyzer>
<tokenizer class="solr.NGramTokenizerFactory"
minGramSize="1" maxGramSize="3"/>
<filter class="solr.LowerCaseFilterFactory"/>
</analyzer>
</fieldType>
After indexing a field like this, the analysis page indicates my queries
should work. If I give it a sample field value of "ABC-123456-SUN" and a
query value of "45" it shows hits in several places, which is what I
expected.
However, when I actually query the field with something like "45" I get
no hits back. Looking at the debugQuery output, it looks like it's
taking my analyzed query text and putting it into a phrase query. So,
for a query of "45" it turns into a phrase query of <field>:"4 5 45"
which then doesn't hit on anything in my index.
What am I missing to make this work?
- Charlie
