`query_string` should use indexed prefixes (#36895)

The QueryStringQueryBuilder does not currently delegate to the field mapper's prefixQuery
method, so does not use indexed prefixes. This commit corrects this.

It also fixes a bug where a query a* would not match the word a if indexed prefixes were used with
a minchar setting of 2.

rest-api-spec/src/main/resources/rest-api-spec/test/search/190_index_prefix_search.yml

@@ -13,15 +13,15 @@ setup:
                 text:
                   type: text
                   index_prefixes:
-                    min_chars: 1
-                    max_chars: 10
+                    min_chars: 2
+                    max_chars: 5
 
   - do:
       index:
           index:  test
           type:   test
           id:     1
-          body:   { text: some short words and a stupendously long one }
+          body:   { text: some short words with a stupendously long one }
 
   - do:
       indices.refresh:
@@ -63,10 +63,11 @@ setup:
         rest_total_hits_as_int: true
         index: test
         body:
+          explain: true
           query:
             query_string:
               default_field: text
-              query: s*
+              query: a*
               boost: 2
 
   - match: {hits.total: 1}

server/src/main/java/org/elasticsearch/index/mapper/TextFieldMapper.java

@@ -33,6 +33,8 @@ import org.apache.lucene.index.IndexOptions;
 import org.apache.lucene.index.IndexableField;
 import org.apache.lucene.index.Term;
 import org.apache.lucene.search.AutomatonQuery;
+import org.apache.lucene.search.BooleanClause;
+import org.apache.lucene.search.BooleanQuery;
 import org.apache.lucene.search.ConstantScoreQuery;
 import org.apache.lucene.search.MultiPhraseQuery;
 import org.apache.lucene.search.MultiTermQuery;
@@ -156,7 +158,7 @@ public class TextFieldMapper extends FieldMapper {
             if (maxChars >= 20) {
                 throw new IllegalArgumentException("max_chars [" + maxChars + "] must be less than 20");
             }
-            this.prefixFieldType = new PrefixFieldType(name() + "._index_prefix", minChars, maxChars);
+            this.prefixFieldType = new PrefixFieldType(name(), name() + "._index_prefix", minChars, maxChars);
             fieldType().setPrefixFieldType(this.prefixFieldType);
             return this;
         }
@@ -347,14 +349,16 @@ public class TextFieldMapper extends FieldMapper {
 
         final int minChars;
         final int maxChars;
+        final String parentField;
 
-        PrefixFieldType(String name, int minChars, int maxChars) {
+        PrefixFieldType(String parentField, String name, int minChars, int maxChars) {
             setTokenized(true);
             setOmitNorms(true);
             setIndexOptions(IndexOptions.DOCS);
             setName(name);
             this.minChars = minChars;
             this.maxChars = maxChars;
+            this.parentField = parentField;
         }
 
         PrefixFieldType setAnalyzer(NamedAnalyzer delegate) {
@@ -387,12 +391,15 @@ public class TextFieldMapper extends FieldMapper {
             Automaton automaton = Operations.concatenate(automata);
             AutomatonQuery query = new AutomatonQuery(new Term(name(), value + "*"), automaton);
             query.setRewriteMethod(method);
-            return query;
+            return new BooleanQuery.Builder()
+                .add(query, BooleanClause.Occur.SHOULD)
+                .add(new TermQuery(new Term(parentField, value)), BooleanClause.Occur.SHOULD)
+                .build();
         }
 
         @Override
         public PrefixFieldType clone() {
-            return new PrefixFieldType(name(), minChars, maxChars);
+            return new PrefixFieldType(parentField, name(), minChars, maxChars);
         }
 
         @Override

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

@@ -42,15 +42,14 @@ import org.apache.lucene.search.spans.SpanNearQuery;
 import org.apache.lucene.search.spans.SpanOrQuery;
 import org.apache.lucene.search.spans.SpanQuery;
 import org.apache.lucene.util.BytesRef;
-import org.elasticsearch.core.internal.io.IOUtils;
 import org.elasticsearch.common.lucene.search.Queries;
 import org.elasticsearch.common.regex.Regex;
 import org.elasticsearch.common.unit.Fuzziness;
+import org.elasticsearch.core.internal.io.IOUtils;
 import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.mapper.FieldNamesFieldMapper;
 import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.index.mapper.MapperService;
-import org.elasticsearch.index.mapper.StringFieldType;
 import org.elasticsearch.index.query.ExistsQueryBuilder;
 import org.elasticsearch.index.query.MultiMatchQueryBuilder;
 import org.elasticsearch.index.query.QueryShardContext;
@@ -507,7 +506,7 @@ public class QueryStringQueryParser extends XQueryParser {
             }
             setAnalyzer(forceAnalyzer == null ? queryBuilder.context.getSearchAnalyzer(currentFieldType) : forceAnalyzer);
             Query query = null;
-            if (currentFieldType instanceof StringFieldType == false) {
+            if (currentFieldType.tokenized() == false) {
                 query = currentFieldType.prefixQuery(termStr, getMultiTermRewriteMethod(), context);
             } else {
                 query = getPossiblyAnalyzedPrefixQuery(currentFieldType.name(), termStr);
@@ -525,7 +524,8 @@ public class QueryStringQueryParser extends XQueryParser {
 
     private Query getPossiblyAnalyzedPrefixQuery(String field, String termStr) throws ParseException {
         if (analyzeWildcard == false) {
-            return super.getPrefixQuery(field, termStr);
+            return currentFieldType.prefixQuery(getAnalyzer().normalize(field, termStr).utf8ToString(),
+                getMultiTermRewriteMethod(), context);
         }
         List<List<String> > tlist;
         // get Analyzer from superclass and tokenize the term
@@ -568,7 +568,7 @@ public class QueryStringQueryParser extends XQueryParser {
         }
 
         if (tlist.size() == 1 && tlist.get(0).size() == 1) {
-            return super.getPrefixQuery(field, tlist.get(0).get(0));
+            return currentFieldType.prefixQuery(tlist.get(0).get(0), getMultiTermRewriteMethod(), context);
         }
 
         // build a boolean query with prefix on the last position only.
@@ -579,7 +579,7 @@ public class QueryStringQueryParser extends XQueryParser {
             Query posQuery;
             if (plist.size() == 1) {
                 if (isLastPos) {
-                    posQuery = super.getPrefixQuery(field, plist.get(0));
+                    posQuery = currentFieldType.prefixQuery(plist.get(0), getMultiTermRewriteMethod(), context);
                 } else {
                     posQuery = newTermQuery(new Term(field, plist.get(0)));
                 }

server/src/test/java/org/elasticsearch/index/mapper/TextFieldTypeTests.java

@@ -21,6 +21,8 @@ package org.elasticsearch.index.mapper;
 import org.apache.lucene.index.IndexOptions;
 import org.apache.lucene.index.Term;
 import org.apache.lucene.search.AutomatonQuery;
+import org.apache.lucene.search.BooleanClause;
+import org.apache.lucene.search.BooleanQuery;
 import org.apache.lucene.search.ConstantScoreQuery;
 import org.apache.lucene.search.FuzzyQuery;
 import org.apache.lucene.search.PrefixQuery;
@@ -40,6 +42,7 @@ import java.util.Arrays;
 import java.util.List;
 
 import static org.apache.lucene.search.MultiTermQuery.CONSTANT_SCORE_REWRITE;
+import static org.hamcrest.Matchers.equalTo;
 
 public class TextFieldTypeTests extends FieldTypeTestCase {
     @Override
@@ -90,7 +93,7 @@ public class TextFieldTypeTests extends FieldTypeTestCase {
                 TextFieldMapper.TextFieldType tft = (TextFieldMapper.TextFieldType)ft;
                 TextFieldMapper.PrefixFieldType pft = tft.getPrefixFieldType();
                 if (pft == null) {
-                    tft.setPrefixFieldType(new TextFieldMapper.PrefixFieldType(ft.name(), 3, 3));
+                    tft.setPrefixFieldType(new TextFieldMapper.PrefixFieldType(ft.name(), ft.name() + "._index_prefix", 3, 3));
                 }
                 else {
                     tft.setPrefixFieldType(null);
@@ -156,7 +159,7 @@ public class TextFieldTypeTests extends FieldTypeTestCase {
     public void testIndexPrefixes() {
         TextFieldMapper.TextFieldType ft = new TextFieldMapper.TextFieldType();
         ft.setName("field");
-        ft.setPrefixFieldType(new TextFieldMapper.PrefixFieldType("field._index_prefix", 2, 10));
+        ft.setPrefixFieldType(new TextFieldMapper.PrefixFieldType("field", "field._index_prefix", 2, 10));
 
         Query q = ft.prefixQuery("goin", CONSTANT_SCORE_REWRITE, null);
         assertEquals(new ConstantScoreQuery(new TermQuery(new Term("field._index_prefix", "goin"))), q);
@@ -167,6 +170,12 @@ public class TextFieldTypeTests extends FieldTypeTestCase {
         q = ft.prefixQuery("g", CONSTANT_SCORE_REWRITE, null);
         Automaton automaton
             = Operations.concatenate(Arrays.asList(Automata.makeChar('g'), Automata.makeAnyChar()));
-        assertEquals(new ConstantScoreQuery(new AutomatonQuery(new Term("field._index_prefix", "g*"), automaton)), q);
+
+        Query expected = new ConstantScoreQuery(new BooleanQuery.Builder()
+            .add(new AutomatonQuery(new Term("field._index_prefix", "g*"), automaton), BooleanClause.Occur.SHOULD)
+            .add(new TermQuery(new Term("field", "g")), BooleanClause.Occur.SHOULD)
+            .build());
+
+        assertThat(q, equalTo(expected));
     }
 }

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

@@ -22,6 +22,7 @@ package org.elasticsearch.index.query;
 import org.apache.lucene.analysis.MockSynonymAnalyzer;
 import org.apache.lucene.index.Term;
 import org.apache.lucene.queries.BlendedTermQuery;
+import org.apache.lucene.search.AutomatonQuery;
 import org.apache.lucene.search.BooleanClause;
 import org.apache.lucene.search.BooleanClause.Occur;
 import org.apache.lucene.search.BooleanQuery;
@@ -45,6 +46,9 @@ import org.apache.lucene.search.spans.SpanNearQuery;
 import org.apache.lucene.search.spans.SpanOrQuery;
 import org.apache.lucene.search.spans.SpanTermQuery;
 import org.apache.lucene.util.BytesRef;
+import org.apache.lucene.util.automaton.Automata;
+import org.apache.lucene.util.automaton.Automaton;
+import org.apache.lucene.util.automaton.Operations;
 import org.apache.lucene.util.automaton.TooComplexToDeterminizeException;
 import org.elasticsearch.Version;
 import org.elasticsearch.action.admin.indices.mapping.put.PutMappingRequest;
@@ -69,6 +73,7 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
+import static org.elasticsearch.common.xcontent.XContentFactory.jsonBuilder;
 import static org.elasticsearch.index.query.AbstractQueryBuilder.parseInnerQueryBuilder;
 import static org.elasticsearch.index.query.QueryBuilders.queryStringQuery;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertBooleanSubQuery;
@@ -78,6 +83,20 @@ import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.instanceOf;
 
 public class QueryStringQueryBuilderTests extends AbstractQueryTestCase<QueryStringQueryBuilder> {
+
+    @Override
+    protected void initializeAdditionalMappings(MapperService mapperService) throws IOException {
+        XContentBuilder mapping = jsonBuilder().startObject().startObject("_doc").startObject("properties")
+            .startObject("prefix_field")
+            .field("type", "text")
+            .startObject("index_prefixes").endObject()
+            .endObject()
+            .endObject().endObject().endObject();
+
+        mapperService.merge("_doc",
+            new CompressedXContent(Strings.toString(mapping)), MapperService.MergeReason.MAPPING_UPDATE);
+    }
+
     @Override
     protected QueryStringQueryBuilder doCreateTestQueryBuilder() {
         int numTerms = randomIntBetween(0, 5);
@@ -535,6 +554,21 @@ public class QueryStringQueryBuilderTests extends AbstractQueryTestCase<QueryStr
         }
     }
 
+    public void testToQueryWildcardWithIndexedPrefixes() throws Exception {
+        QueryStringQueryParser queryParser = new QueryStringQueryParser(createShardContext(), "prefix_field");
+        Query query = queryParser.parse("foo*");
+        Query expectedQuery = new ConstantScoreQuery(new TermQuery(new Term("prefix_field._index_prefix", "foo")));
+        assertThat(query, equalTo(expectedQuery));
+
+        query = queryParser.parse("g*");
+        Automaton a = Operations.concatenate(Arrays.asList(Automata.makeChar('g'), Automata.makeAnyChar()));
+        expectedQuery = new ConstantScoreQuery(new BooleanQuery.Builder()
+            .add(new AutomatonQuery(new Term("prefix_field._index_prefix", "g*"), a), Occur.SHOULD)
+            .add(new TermQuery(new Term("prefix_field", "g")), Occur.SHOULD)
+            .build());
+        assertThat(query, equalTo(expectedQuery));
+    }
+
     public void testToQueryWilcardQueryWithSynonyms() throws Exception {
         for (Operator op : Operator.values()) {
             BooleanClause.Occur defaultOp = op.toBooleanClauseOccur();