There are a lot of different use cases and the separate analyzers for indexing and query is part of the Solr power. For example, you could apply ngram during indexing time to generate multiple substrings. But you don't want to do that during the query, because otherwise you are matching on 'shared prefix' instead of on what user entered. Thinking phone number directory where people may enter any suffix and you want to match it. See for example https://www.slideshare.net/arafalov/rapid-solr-schema-development-phone-directory , starting slide 16 onwards.
Or, for non-production but fun use case: https://github.com/arafalov/solr-thai-test/blob/master/collection1/conf/schema.xml#L34-L55 (search phonetically mapped Thai text in English). Similarly, you may want to apply synonyms at query time only if you want to avoid diluting some relevancy. Or at index type to normalize spelling and help relevancy. Or you may want to be doing some accent folding for sorting or faceting (which uses indexed tokens). Regards, Alex. On Thu, 10 Sep 2020 at 11:19, Steven White <swhite4...@gmail.com> wrote: > > Hi everyone, > > In Solr's schema, I have come across field types that use a different logic > for "index" than for "query". To be clear, I"m talking about this block: > > <fieldType name="text_en" class="solr.TextField" > positionIncrementGap="100"> > <analyzer type="index"> > <!-- what you see in this block doesn't have to be the same as what you > see inside "query" block --> > </analyzer> > <analyzer type="query"> > <!-- what you see in this block doesn't have to be the same as what you > see inside "index" block --> > </analyzer> > </fieldType> > > Why would one want to not use the same logic for both and simply use: > > <fieldType name="text_en" class="solr.TextField" > positionIncrementGap="100"> > <analyzer> > <!-- same logic to be used by for "index" and "query" --> > </analyzer> > </fieldType> > > What are real word use cases to use a different analyzer for index and > query? > > Thanks, > > Steve
