Implicit match all when using not filters

Ivan · April 4, 2013, 5:56pm

Besides working on projects using ElasticSearch, I am still using on Lucene
as well. One limitation of Lucene is that a query or sub-query cannot
continue only NOT clauses. The common workaround is to ask for everything
: when using a NOT clause.

I believe ElasticSearch does this automatically when using NOT clauses. I
am looking to borrow coughstealcough some ideas, but I can't figure
where exactly in the code this magic is happening. Anyone have any ideas
where it could be? Imitation is the sincerest form of flattery.

Cheers,

Ivan

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Igor_Motov · April 5, 2013, 1:51pm

github.com

elastic/elasticsearch/blob/4eefcb9c82778e8cd7a0126b98872cf08740c46e/src/main/java/org/elasticsearch/common/lucene/search/Queries.java#L103


      
              List<BooleanClause> clauses = ((BooleanQuery) q).clauses();
              if (clauses.isEmpty()) {
                  return false;
              }
              for (BooleanClause clause : clauses) {
                  if (!clause.isProhibited()) return false;
              }
              return true;
          }
          
          public static Query fixNegativeQueryIfNeeded(Query q) {
              if (isNegativeQuery(q)) {
                  BooleanQuery newBq = (BooleanQuery) q.clone();
                  newBq.add(MATCH_ALL_QUERY, BooleanClause.Occur.MUST);
                  return newBq;
              }
              return q;
          }
          
          public static boolean isConstantMatchAllQuery(Query query) {
              if (query == Queries.MATCH_ALL_QUERY) {

On Thursday, April 4, 2013 1:56:12 PM UTC-4, Ivan Brusic wrote:

Besides working on projects using Elasticsearch, I am still using on
Lucene as well. One limitation of Lucene is that a query or sub-query
cannot continue only NOT clauses. The common workaround is to ask for
everything : when using a NOT clause.

I believe Elasticsearch does this automatically when using NOT clauses. I
am looking to borrow coughstealcough some ideas, but I can't figure
where exactly in the code this magic is happening. Anyone have any ideas
where it could be? Imitation is the sincerest form of flattery.

Cheers,

Ivan

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Ivan · April 5, 2013, 4:39pm

Thanks so much. I was looking in the Builder classes, while the call was in
the parser instead.

I knew I would learn something. My code is pretty much identical, except I
didn't know about the existence of isProhibited(). Not sure how I missed it
after many years of using Lucene.

--
Ivan

On Fri, Apr 5, 2013 at 6:51 AM, Igor Motov imotov@gmail.com wrote:

https://github.com/elasticsearch/elasticsearch/blob/4eefcb9c82778e8cd7a0126b98872cf08740c46e/src/main/java/org/elasticsearch/common/lucene/search/Queries.java#L103

On Thursday, April 4, 2013 1:56:12 PM UTC-4, Ivan Brusic wrote:

Besides working on projects using Elasticsearch, I am still using on
Lucene as well. One limitation of Lucene is that a query or sub-query
cannot continue only NOT clauses. The common workaround is to ask for
everything : when using a NOT clause.

I believe Elasticsearch does this automatically when using NOT clauses. I
am looking to borrow coughstealcough some ideas, but I can't figure
where exactly in the code this magic is happening. Anyone have any ideas
where it could be? Imitation is the sincerest form of flattery.

Cheers,

Ivan

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"elasticsearch" group.
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