How to utilize a Lucene Query class (CommonTermsQuery) with SolrJ - solr

Question

I want to use Lucene's CommonTermsQuery class for a query executed with SolrJ, so how do I utilize Lucene's Query classes? And what are the differences between those classes and what appears to be Solr's query parsers?

Answer 1

Solr currently doesn't include a query parser that uses CommonTermsQuery, but you can add your own query parsers to Solr by compiling a .jar by yourself and then adding that jar in a <lib .. directive in solrconfig.xml.
There's an existing example on how to make a QParserPlugin for Solr with CommonTermsQuery available as a gist, so that's probably a good place to start for a custom plugin. You'll select the custom QueryParser through the standard {!syntax} in start of a query. Since SolrJ is just the client talking to a Solr server, the plugin itself has to be implemented and loaded on the server (or if you're running in SolrCloud / Cluster mode, on all servers).
A Query Parser takes free form text (which is what Solr is great at) and converts it into a set of Query classes for Lucene to execute (which represents the query, in the way that the query parser thought that the user wanted to express herself).
The differences between Solr's query parser and Lucene's query parser are several, but most people use the edismax or dismax query parser these days (these may have evolved into the Lucene QP over time as well unknown to me):
Differences in the Solr Query Parser include (these are from an older page on the Solr Wiki - I'm not sure if there's a more recent version available, but since Solr and Lucene's code merged into a single tree and got synchronized, I guess there are less new differences introduced compared to when they were separate projects):
Range queries [a TO z], prefix queries a*, and wildcard queries a*b are constant-scoring (all matching documents get an equal score). The scoring factors tf, idf, index boost, and coord are not used. There is no limitation on the number of terms that match (as there was in past versions of Lucene).
Lucene 2.1 has also switched to use ConstantScoreRangeQuery for its range queries.
A * may be used for either or both endpoints to specify an open-ended range query.
field:[* TO 100] finds all field values less than or equal to 100
field:[100 TO *] finds all field values greater than or equal to 100
field:[* TO *] matches all documents with the field
Pure negative queries (all clauses prohibited) are allowed.
-inStock:false finds all field values where inStock is not false
-field:[* TO *] finds all documents without a value for field
A hook into FunctionQuery syntax. Quotes will be necessary to encapsulate the function when it includes parentheses.
Example: _val_:myfield
Example: _val_:"recip(rord(myfield),1,2,3)"
Nested query support for any type of query parser (via QParserPlugin).
Quotes will often be necessary to encapsulate the nested query if it contains reserved characters.
Example: query:"{!dismax qf=myfield}how now brown cow"