Fix (simple)_query_string to ignore removed terms (#28871)

This change ensures that we ignore terms removed from the analysis rather than returning a match_no_docs query for the part
that contain the stop word. For instance a query like "the AND fox" should ignore "the" if it is considered as a stop word instead of
adding a match_no_docs query.
This change also fixes the analysis of prefix terms that start with a stop word (e.g. `the*`). In such case if `analyze_wildcard` is true and `the`
is considered as a stop word this part of the query is rewritten into a match_no_docs query. Since it's a prefix query this change forces the prefix query
on `the` even if it is removed from the analysis.

Fixes #28855
Fixes #28856

server/src/main/java/org/elasticsearch/index/search/MatchQuery.java

@@ -102,7 +102,10 @@ public class MatchQuery {
 
     public enum ZeroTermsQuery implements Writeable {
         NONE(0),
-        ALL(1);
+        ALL(1),
+        // this is used internally to make sure that query_string and simple_query_string
+        // ignores query part that removes all tokens.
+        NULL(2);
 
         private final int ordinal;
 
@@ -312,10 +315,16 @@ public class MatchQuery {
     }
 
     protected Query zeroTermsQuery() {
-        if (zeroTermsQuery == DEFAULT_ZERO_TERMS_QUERY) {
+        switch (zeroTermsQuery) {
-            return Queries.newMatchNoDocsQuery("Matching no documents because no terms present.");
+            case NULL:
+                return null;
+            case NONE:
+                return Queries.newMatchNoDocsQuery("Matching no documents because no terms present");
+            case ALL:
+                return Queries.newMatchAllQuery();
+            default:
+                throw new IllegalStateException("unknown zeroTermsQuery " + zeroTermsQuery);
         }
-        return Queries.newMatchAllQuery();
     }
 
     private class MatchQueryBuilder extends QueryBuilder {

server/src/main/java/org/elasticsearch/index/search/QueryStringQueryParser.java

@@ -147,6 +147,7 @@ public class QueryStringQueryParser extends XQueryParser {
         this.context = context;
         this.fieldsAndWeights = Collections.unmodifiableMap(fieldsAndWeights);
         this.queryBuilder = new MultiMatchQuery(context);
+        queryBuilder.setZeroTermsQuery(MatchQuery.ZeroTermsQuery.NULL);
         queryBuilder.setLenient(lenient);
         this.lenient = lenient;
     }
@@ -343,7 +344,6 @@ public class QueryStringQueryParser extends XQueryParser {
         if (fields.isEmpty()) {
             return newUnmappedFieldQuery(field);
         }
-        final Query query;
         Analyzer oldAnalyzer = queryBuilder.analyzer;
         int oldSlop = queryBuilder.phraseSlop;
         try {
@@ -353,7 +353,7 @@ public class QueryStringQueryParser extends XQueryParser {
                 queryBuilder.setAnalyzer(forceAnalyzer);
             }
             queryBuilder.setPhraseSlop(slop);
-            query = queryBuilder.parse(MultiMatchQueryBuilder.Type.PHRASE, fields, queryText, null);
+            Query query = queryBuilder.parse(MultiMatchQueryBuilder.Type.PHRASE, fields, queryText, null);
             return applySlop(query, slop);
         } catch (IOException e) {
             throw new ParseException(e.getMessage());
@@ -555,7 +555,7 @@ public class QueryStringQueryParser extends XQueryParser {
         }
 
         if (tlist.size() == 0) {
-            return new MatchNoDocsQuery("analysis was empty for " + field + ":" + termStr);
+            return super.getPrefixQuery(field, termStr);
         }
 
         if (tlist.size() == 1 && tlist.get(0).size() == 1) {
@@ -763,7 +763,7 @@ public class QueryStringQueryParser extends XQueryParser {
     @Override
     public Query parse(String query) throws ParseException {
         if (query.trim().isEmpty()) {
-            return queryBuilder.zeroTermsQuery();
+            return Queries.newMatchNoDocsQuery("Matching no documents because no terms present");
         }
         return super.parse(query);
     }

server/src/main/java/org/elasticsearch/index/search/SimpleQueryStringQueryParser.java

@@ -74,6 +74,7 @@ public class SimpleQueryStringQueryParser extends SimpleQueryParser {
         this.queryBuilder = new MultiMatchQuery(context);
         this.queryBuilder.setAutoGenerateSynonymsPhraseQuery(settings.autoGenerateSynonymsPhraseQuery());
         this.queryBuilder.setLenient(settings.lenient());
+        this.queryBuilder.setZeroTermsQuery(MatchQuery.ZeroTermsQuery.NULL);
         if (analyzer != null) {
             this.queryBuilder.setAnalyzer(analyzer);
         }

server/src/test/java/org/elasticsearch/index/query/MatchQueryBuilderTests.java

@@ -111,7 +111,7 @@ public class MatchQueryBuilderTests extends AbstractQueryTestCase<MatchQueryBuil
         }
 
         if (randomBoolean()) {
-            matchQuery.zeroTermsQuery(randomFrom(MatchQuery.ZeroTermsQuery.values()));
+            matchQuery.zeroTermsQuery(randomFrom(ZeroTermsQuery.ALL, ZeroTermsQuery.NONE));
         }
 
         if (randomBoolean()) {

server/src/test/java/org/elasticsearch/index/query/MultiMatchQueryBuilderTests.java

@@ -129,7 +129,7 @@ public class MultiMatchQueryBuilderTests extends AbstractQueryTestCase<MultiMatc
             query.cutoffFrequency((float) 10 / randomIntBetween(1, 100));
         }
         if (randomBoolean()) {
-            query.zeroTermsQuery(randomFrom(MatchQuery.ZeroTermsQuery.values()));
+            query.zeroTermsQuery(randomFrom(MatchQuery.ZeroTermsQuery.NONE, MatchQuery.ZeroTermsQuery.ALL));
         }
         if (randomBoolean()) {
             query.autoGenerateSynonymsPhraseQuery(randomBoolean());

server/src/test/java/org/elasticsearch/index/query/QueryStringQueryBuilderTests.java

@@ -1052,6 +1052,33 @@ public class QueryStringQueryBuilderTests extends AbstractQueryTestCase<QueryStr
         assertEquals(expected, query);
     }
 
+    public void testWithStopWords() throws Exception {
+        assumeTrue("test runs only when at least a type is registered", getCurrentTypes().length > 0);
+        Query query = new QueryStringQueryBuilder("the quick fox")
+            .field(STRING_FIELD_NAME)
+            .analyzer("english")
+            .toQuery(createShardContext());
+        BooleanQuery expected = new BooleanQuery.Builder()
+            .add(new TermQuery(new Term(STRING_FIELD_NAME, "quick")), Occur.SHOULD)
+            .add(new TermQuery(new Term(STRING_FIELD_NAME, "fox")), Occur.SHOULD)
+            .build();
+        assertEquals(expected, query);
+    }
+
+    public void testWithPrefixStopWords() throws Exception {
+        assumeTrue("test runs only when at least a type is registered", getCurrentTypes().length > 0);
+        Query query = new QueryStringQueryBuilder("the* quick fox")
+            .field(STRING_FIELD_NAME)
+            .analyzer("english")
+            .toQuery(createShardContext());
+        BooleanQuery expected = new BooleanQuery.Builder()
+            .add(new PrefixQuery(new Term(STRING_FIELD_NAME, "the")), Occur.SHOULD)
+            .add(new TermQuery(new Term(STRING_FIELD_NAME, "quick")), Occur.SHOULD)
+            .add(new TermQuery(new Term(STRING_FIELD_NAME, "fox")), Occur.SHOULD)
+            .build();
+        assertEquals(expected, query);
+    }
+
     private static IndexMetaData newIndexMeta(String name, Settings oldIndexSettings, Settings indexSettings) {
         Settings build = Settings.builder().put(oldIndexSettings)
             .put(indexSettings)

server/src/test/java/org/elasticsearch/index/query/SimpleQueryStringBuilderTests.java

@@ -625,6 +625,33 @@ public class SimpleQueryStringBuilderTests extends AbstractQueryTestCase<SimpleQ
         assertEquals(expected, query);
     }
 
+    public void testWithStopWords() throws Exception {
+        assumeTrue("test runs only when at least a type is registered", getCurrentTypes().length > 0);
+        Query query = new SimpleQueryStringBuilder("the quick fox")
+            .field(STRING_FIELD_NAME)
+            .analyzer("english")
+            .toQuery(createShardContext());
+        BooleanQuery expected = new BooleanQuery.Builder()
+            .add(new TermQuery(new Term(STRING_FIELD_NAME, "quick")), BooleanClause.Occur.SHOULD)
+            .add(new TermQuery(new Term(STRING_FIELD_NAME, "fox")), BooleanClause.Occur.SHOULD)
+            .build();
+        assertEquals(expected, query);
+    }
+
+    public void testWithPrefixStopWords() throws Exception {
+        assumeTrue("test runs only when at least a type is registered", getCurrentTypes().length > 0);
+        Query query = new SimpleQueryStringBuilder("the* quick fox")
+            .field(STRING_FIELD_NAME)
+            .analyzer("english")
+            .toQuery(createShardContext());
+        BooleanQuery expected = new BooleanQuery.Builder()
+            .add(new PrefixQuery(new Term(STRING_FIELD_NAME, "the")), BooleanClause.Occur.SHOULD)
+            .add(new TermQuery(new Term(STRING_FIELD_NAME, "quick")), BooleanClause.Occur.SHOULD)
+            .add(new TermQuery(new Term(STRING_FIELD_NAME, "fox")), BooleanClause.Occur.SHOULD)
+            .build();
+        assertEquals(expected, query);
+    }
+
     private static IndexMetaData newIndexMeta(String name, Settings oldIndexSettings, Settings indexSettings) {
         Settings build = Settings.builder().put(oldIndexSettings)
             .put(indexSettings)