You're welcome, great to hear you have less doubts.
I see you're using the SynonymGraphFilter followed by a StopFilter at
query time: have a look at this post [1], you might find some useful info.
Best,
Andrea
[1] https://sease.io/2018/07/combining-synonyms-and-stopwords.html
On 15/08/18 21:47, Zimmermann, Thomas wrote:
Hi Andrea,
Thanks so much. I wasn¹t thinking in the correct perspective on the query
portion of the analyzer, but your explanation makes perfect sense. In my
head I imagine the result set of the query being transformed by the
filters, but in actuality the filter is being applied to the query itself
before processing. This makes sense on my end and I think it answer my
questions.
Excellent point on the html strip factory. I¹ll evaluate our use cases.
This was all brought about by switching from the deprecated synonym and
word delimiter factories to the new graph based factories, where we
stopped filtering on insert for those and switched to filtering on query
based on recommendations from the Solr Doc.
Thanks,
TZ
On 8/15/18, 3:17 PM, "Andrea Gazzarini" <a.gazzar...@sease.io> wrote:
Hi Thomas,
as you know, the two analyzers play in a different moment, with a
different input and a different goal for the corresponding output:
* index analyzer: input is a field value, output is used for building
the index
* query analyzer: input is a (user) query string, output is used for
building a (Solr) query
At index time a term dictionary is built, and a retrieval time the
output query tries to find a match in that dictionary. I wouldn't call
it "redundancy" because even if the filter is the same, it is applied to
a different input and it has a different goal.
Some filters must be present both at index at query time because
otherwise you won't find any match: if you put a lowercase filter only
on the index side, queries with uppercase chars won't find any match.
Some others don't (one example is the SynonymGraphFilter you've used
only at query time). In general, everything depends on your needs and
it's perfectly valid to have symmetric (index analyzer = query analyzer)
and asymmetric text analysis (index analyzer != query analyzer).
Without knowing your context is very hard to guess if there's something
wrong in the configuration. What is the part of the analyzers you think
is redundant?
On top of that: in your chain the HTMLStripCharFilterFactory applied at
query time is something unusual, because while it makes perfectly sense
at index time (where I guess you index some HTML source), at query time
I can't imagine a scenario where the user inputs queries containing HTML
tags.
Best,
Andrea
On 15/08/18 20:43, Zimmermann, Thomas wrote:
Hi,
We have the text field below configured on fields that are both stored
and indexed. It seems to me that applying the same filters on both index
and query would be redundant, and perhaps a waste of processing on the
retrieval side if the filter work was already done on the index side. Is
this a fair statement to make? Should I only be applying filters on one
end of the transaction?
Thanks,
TZ
<fieldType name="text" class="solr.TextField"
positionIncrementGap="100">
<analyzer type="index">
<charFilter class="solr.HTMLStripCharFilterFactory"/>
<tokenizer class="solr.WhitespaceTokenizerFactory"/>
<filter class="solr.StopFilterFactory" ignoreCase="true"
words="stopwords.txt" />
<filter class="solr.LowerCaseFilterFactory"/>
<filter class="solr.SnowballPorterFilterFactory"
language="English" protected="protwords.txt"/>
<filter class="solr.RemoveDuplicatesTokenFilterFactory"/>
</analyzer>
<analyzer type="query">
<charFilter class="solr.HTMLStripCharFilterFactory"/>
<tokenizer class="solr.WhitespaceTokenizerFactory"/>
<filter class="solr.SynonymGraphFilterFactory"
synonyms="synonyms.txt" ignoreCase="true" expand="true"/>
<filter class="solr.StopFilterFactory" ignoreCase="true"
words="stopwords.txt" />
<filter class="solr.WordDelimiterGraphFilterFactory"
generateWordParts="1" generateNumberParts="1" catenateWords="0"
catenateNumbers="0" catenateAll="0" splitOnCaseChange="1"/>
<filter class="solr.LowerCaseFilterFactory"/>
<filter class="solr.SnowballPorterFilterFactory"
language="English" protected="protwords.txt"/>
<filter class="solr.RemoveDuplicatesTokenFilterFactory"/>
</analyzer>
</fieldType>
