Refactor field expansion for match, multi_match and query_string query (#25726)

This commit changes the way we handle field expansion in `match`, `multi_match` and `query_string` query.
 The main changes are:

- For exact field name, the new behavior is to rewrite to a matchnodocs query when the field name is not found in the mapping.

- For partial field names (with `*` suffix), the expansion is done only on `keyword`, `text`, `date`, `ip` and `number` field types. Other field types are simply ignored.

- For all fields (`*`), the expansion is done on accepted field types only (see above) and metadata fields are also filtered.

- The `*` notation can also be used to set `default_field` option on`query_string` query. This should replace the needs for the extra option `use_all_fields` which is deprecated in this change.

This commit also rewrites simple `*` query to matchalldocs query when all fields are requested (Fixes #25556). 

The same change should be done on `simple_query_string` for completeness.

`use_all_fields` option in `query_string` is also deprecated in this change, `default_field` should be set to `*` instead.

Relates #25551

core/src/main/java/org/elasticsearch/common/lucene/search/Queries.java

@@ -30,6 +30,7 @@ import org.apache.lucene.search.MatchNoDocsQuery;
 import org.apache.lucene.search.PrefixQuery;
 import org.apache.lucene.search.Query;
 import org.apache.lucene.util.BytesRef;
+import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.index.mapper.TypeFieldMapper;
 
@@ -47,6 +48,16 @@ public class Queries {
         return new MatchNoDocsQuery(reason);
     }
 
+
+    public static Query newUnmappedFieldQuery(String field) {
+        return Queries.newMatchNoDocsQuery("unmapped field [" + (field != null ? field : "null") + "]");
+    }
+
+    public static Query newLenientFieldQuery(String field, RuntimeException e) {
+        String message = ElasticsearchException.getExceptionName(e) + ":[" + e.getMessage() + "]";
+        return Queries.newMatchNoDocsQuery("failed [" + field + "] query, caused by " + message);
+    }
+
     public static Query newNestedFilter() {
         return new PrefixQuery(new Term(TypeFieldMapper.NAME, new BytesRef("__")));
     }

core/src/main/java/org/elasticsearch/index/query/MultiMatchQueryBuilder.java

@@ -36,6 +36,7 @@ import org.elasticsearch.index.mapper.MapperService;
 import org.elasticsearch.index.query.support.QueryParsers;
 import org.elasticsearch.index.search.MatchQuery;
 import org.elasticsearch.index.search.MultiMatchQuery;
+import org.elasticsearch.index.search.QueryStringQueryParser;
 
 import java.io.IOException;
 import java.util.HashMap;
@@ -739,27 +740,10 @@ public class MultiMatchQueryBuilder extends AbstractQueryBuilder<MultiMatchQuery
             }
         }
 
-        Map<String, Float> newFieldsBoosts = handleFieldsMatchPattern(context.getMapperService(), fieldsBoosts);
-
+        Map<String, Float> newFieldsBoosts = QueryStringQueryParser.resolveMappingFields(context, fieldsBoosts);
         return multiMatchQuery.parse(type, newFieldsBoosts, value, minimumShouldMatch);
     }
 
-    private static Map<String, Float> handleFieldsMatchPattern(MapperService mapperService, Map<String, Float> fieldsBoosts) {
-        Map<String, Float> newFieldsBoosts = new TreeMap<>();
-        for (Map.Entry<String, Float> fieldBoost : fieldsBoosts.entrySet()) {
-            String fField = fieldBoost.getKey();
-            Float fBoost = fieldBoost.getValue();
-            if (Regex.isSimpleMatchPattern(fField)) {
-                for (String field : mapperService.simpleMatchToIndexNames(fField)) {
-                    newFieldsBoosts.put(field, fBoost);
-                }
-            } else {
-                newFieldsBoosts.put(fField, fBoost);
-            }
-        }
-        return newFieldsBoosts;
-    }
-
     @Override
     protected int doHashCode() {
         return Objects.hash(value, fieldsBoosts, type, operator, analyzer, slop, fuzziness,

core/src/main/java/org/elasticsearch/index/query/QueryStringQueryBuilder.java

@@ -34,28 +34,17 @@ import org.elasticsearch.common.unit.Fuzziness;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.analysis.NamedAnalyzer;
-import org.elasticsearch.index.mapper.DateFieldMapper;
-import org.elasticsearch.index.mapper.IpFieldMapper;
-import org.elasticsearch.index.mapper.KeywordFieldMapper;
-import org.elasticsearch.index.mapper.MappedFieldType;
-import org.elasticsearch.index.mapper.MapperService;
-import org.elasticsearch.index.mapper.NumberFieldMapper;
-import org.elasticsearch.index.mapper.ScaledFloatFieldMapper;
-import org.elasticsearch.index.mapper.TextFieldMapper;
 import org.elasticsearch.index.query.support.QueryParsers;
 import org.elasticsearch.index.search.QueryStringQueryParser;
 import org.joda.time.DateTimeZone;
 
 import java.io.IOException;
 import java.util.ArrayList;
-import java.util.Collection;
 import java.util.HashMap;
-import java.util.HashSet;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
-import java.util.Set;
 import java.util.TreeMap;
 
 /**
@@ -110,24 +99,10 @@ public class QueryStringQueryBuilder extends AbstractQueryBuilder<QueryStringQue
     private static final ParseField TIME_ZONE_FIELD = new ParseField("time_zone");
     private static final ParseField SPLIT_ON_WHITESPACE = new ParseField("split_on_whitespace")
             .withAllDeprecated("This setting is ignored, the parser always splits on logical operator");
-    private static final ParseField ALL_FIELDS_FIELD = new ParseField("all_fields");
+    private static final ParseField ALL_FIELDS_FIELD = new ParseField("all_fields")
+            .withAllDeprecated("Set [default_field] to `*` instead");
     private static final ParseField TYPE_FIELD = new ParseField("type");
 
-    // Mapping types the "all-ish" query can be executed against
-    public static final Set<String> ALLOWED_QUERY_MAPPER_TYPES;
-
-    static {
-        ALLOWED_QUERY_MAPPER_TYPES = new HashSet<>();
-        ALLOWED_QUERY_MAPPER_TYPES.add(DateFieldMapper.CONTENT_TYPE);
-        ALLOWED_QUERY_MAPPER_TYPES.add(IpFieldMapper.CONTENT_TYPE);
-        ALLOWED_QUERY_MAPPER_TYPES.add(KeywordFieldMapper.CONTENT_TYPE);
-        for (NumberFieldMapper.NumberType nt : NumberFieldMapper.NumberType.values()) {
-            ALLOWED_QUERY_MAPPER_TYPES.add(nt.typeName());
-        }
-        ALLOWED_QUERY_MAPPER_TYPES.add(ScaledFloatFieldMapper.CONTENT_TYPE);
-        ALLOWED_QUERY_MAPPER_TYPES.add(TextFieldMapper.CONTENT_TYPE);
-    }
-
     private final String queryString;
 
     private String defaultField;
@@ -179,8 +154,6 @@ public class QueryStringQueryBuilder extends AbstractQueryBuilder<QueryStringQue
 
     private DateTimeZone timeZone;
 
-    private Boolean useAllFields;
-
     /** To limit effort spent determinizing regexp queries. */
     private int maxDeterminizedStates = DEFAULT_MAX_DETERMINED_STATES;
 
@@ -240,8 +213,11 @@ public class QueryStringQueryBuilder extends AbstractQueryBuilder<QueryStringQue
         if (in.getVersion().onOrAfter(Version.V_5_1_1)) {
             if (in.getVersion().before(Version.V_6_0_0_beta1)) {
                 in.readBoolean(); // split_on_whitespace
+                Boolean useAllField = in.readOptionalBoolean();
+                if (useAllField != null && useAllField) {
+                    defaultField = "*";
+                }
             }
-            useAllFields = in.readOptionalBoolean();
         }
     }
 
@@ -291,8 +267,9 @@ public class QueryStringQueryBuilder extends AbstractQueryBuilder<QueryStringQue
         if (out.getVersion().onOrAfter(Version.V_5_1_1)) {
             if (out.getVersion().before(Version.V_6_0_0_beta1)) {
                 out.writeBoolean(false); // split_on_whitespace
+                Boolean useAllFields = defaultField == null ? null : Regex.isMatchAllPattern(defaultField);
+                out.writeOptionalBoolean(useAllFields);
             }
-            out.writeOptionalBoolean(this.useAllFields);
         }
     }
 
@@ -314,17 +291,19 @@ public class QueryStringQueryBuilder extends AbstractQueryBuilder<QueryStringQue
     }
 
     /**
-     * Tell the query_string query to use all fields explicitly, even if _all is
-     * enabled. If the "default_field" parameter or "fields" are specified, they
-     * will be ignored.
+     * This setting is deprecated, set {@link #defaultField(String)} to "*" instead.
      */
+    @Deprecated
     public QueryStringQueryBuilder useAllFields(Boolean useAllFields) {
-        this.useAllFields = useAllFields;
+        if (useAllFields) {
+            this.defaultField = "*";
+        }
         return this;
     }
 
+    @Deprecated
     public Boolean useAllFields() {
-        return this.useAllFields;
+        return defaultField == null ? null : Regex.isMatchAllPattern(defaultField);
     }
 
     /**
@@ -703,9 +682,6 @@ public class QueryStringQueryBuilder extends AbstractQueryBuilder<QueryStringQue
             builder.field(TIME_ZONE_FIELD.getPreferredName(), this.timeZone.getID());
         }
         builder.field(ESCAPE_FIELD.getPreferredName(), this.escape);
-        if (this.useAllFields != null) {
-            builder.field(ALL_FIELDS_FIELD.getPreferredName(), this.useAllFields);
-        }
         printBoostAndQueryName(builder);
         builder.endObject();
     }
@@ -737,7 +713,6 @@ public class QueryStringQueryBuilder extends AbstractQueryBuilder<QueryStringQue
         Fuzziness fuzziness = QueryStringQueryBuilder.DEFAULT_FUZZINESS;
         String fuzzyRewrite = null;
         String rewrite = null;
-        Boolean useAllFields = null;
         Map<String, Float> fieldsAndWeights = new HashMap<>();
         while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
             if (token == XContentParser.Token.FIELD_NAME) {
@@ -812,7 +787,7 @@ public class QueryStringQueryBuilder extends AbstractQueryBuilder<QueryStringQue
                 } else if (LENIENT_FIELD.match(currentFieldName)) {
                     lenient = parser.booleanValue();
                 } else if (ALL_FIELDS_FIELD.match(currentFieldName)) {
-                    useAllFields = parser.booleanValue();
+                    defaultField = "*";
                 } else if (MAX_DETERMINIZED_STATES_FIELD.match(currentFieldName)) {
                     maxDeterminizedStates = parser.intValue();
                 } else if (TIME_ZONE_FIELD.match(currentFieldName)) {
@@ -847,12 +822,6 @@ public class QueryStringQueryBuilder extends AbstractQueryBuilder<QueryStringQue
             throw new ParsingException(parser.getTokenLocation(), "[" + QueryStringQueryBuilder.NAME + "] must be provided with a [query]");
         }
 
-        if ((useAllFields != null && useAllFields) &&
-                (defaultField != null || fieldsAndWeights.size() != 0)) {
-            throw new ParsingException(parser.getTokenLocation(),
-                    "cannot use [all_fields] parameter in conjunction with [default_field] or [fields]");
-        }
-
         QueryStringQueryBuilder queryStringQuery = new QueryStringQueryBuilder(queryString);
         queryStringQuery.fields(fieldsAndWeights);
         queryStringQuery.defaultField(defaultField);
@@ -880,7 +849,6 @@ public class QueryStringQueryBuilder extends AbstractQueryBuilder<QueryStringQue
         queryStringQuery.timeZone(timeZone);
         queryStringQuery.boost(boost);
         queryStringQuery.queryName(queryName);
-        queryStringQuery.useAllFields(useAllFields);
         return queryStringQuery;
     }
 
@@ -914,8 +882,7 @@ public class QueryStringQueryBuilder extends AbstractQueryBuilder<QueryStringQue
                 timeZone == null ? other.timeZone == null : other.timeZone != null &&
                 Objects.equals(timeZone.getID(), other.timeZone.getID()) &&
                 Objects.equals(escape, other.escape) &&
-                Objects.equals(maxDeterminizedStates, other.maxDeterminizedStates) &&
-                Objects.equals(useAllFields, other.useAllFields);
+                Objects.equals(maxDeterminizedStates, other.maxDeterminizedStates);
     }
 
     @Override
@@ -924,72 +891,37 @@ public class QueryStringQueryBuilder extends AbstractQueryBuilder<QueryStringQue
                 quoteFieldSuffix, allowLeadingWildcard, analyzeWildcard,
                 enablePositionIncrements, fuzziness, fuzzyPrefixLength,
                 fuzzyMaxExpansions, fuzzyRewrite, phraseSlop, type, tieBreaker, rewrite, minimumShouldMatch, lenient,
-                timeZone == null ? 0 : timeZone.getID(), escape, maxDeterminizedStates, useAllFields);
-    }
-
-    /**
-     * Given a shard context, return a map of all fields in the mappings that
-     * can be queried. The map will be field name to a float of 1.0f.
-     */
-    public static Map<String, Float> allQueryableDefaultFields(QueryShardContext context) {
-        Collection<String> allFields = context.simpleMatchToIndexNames("*");
-        Map<String, Float> fields = new HashMap<>();
-        for (String fieldName : allFields) {
-            if (MapperService.isMetadataField(fieldName)) {
-                // Ignore our metadata fields
-                continue;
-            }
-            MappedFieldType mft = context.fieldMapper(fieldName);
-            assert mft != null : "should never have a null mapper for an existing field";
-
-            // Ignore fields that are not in the allowed mapper types. Some
-            // types do not support term queries, and thus we cannot generate
-            // a special query for them.
-            String mappingType = mft.typeName();
-            if (ALLOWED_QUERY_MAPPER_TYPES.contains(mappingType)) {
-                fields.put(fieldName, 1.0f);
-            }
-        }
-        return fields;
+                timeZone == null ? 0 : timeZone.getID(), escape, maxDeterminizedStates);
     }
 
     @Override
     protected Query doToQuery(QueryShardContext context) throws IOException {
         String rewrittenQueryString = escape ? org.apache.lucene.queryparser.classic.QueryParser.escape(this.queryString) : queryString;
-        if ((useAllFields != null && useAllFields) && (fieldsAndWeights.size() != 0 || this.defaultField != null)) {
-            throw addValidationError("cannot use [all_fields] parameter in conjunction with [default_field] or [fields]", null);
+        if (fieldsAndWeights.size() > 0 && this.defaultField != null) {
+            throw addValidationError("cannot use [fields] parameter in conjunction with [default_field]", null);
         }
 
         QueryStringQueryParser queryParser;
         boolean isLenient = lenient == null ? context.queryStringLenient() : lenient;
         if (defaultField != null) {
-            queryParser = new QueryStringQueryParser(context, defaultField, isLenient);
-        } else if (fieldsAndWeights.size() > 0) {
-            final Map<String, Float> resolvedFields = new TreeMap<>();
-            for (Map.Entry<String, Float> fieldsEntry : fieldsAndWeights.entrySet()) {
-                String fieldName = fieldsEntry.getKey();
-                Float weight = fieldsEntry.getValue();
-                if (Regex.isSimpleMatchPattern(fieldName)) {
-                    for (String resolvedFieldName : context.getMapperService().simpleMatchToIndexNames(fieldName)) {
-                        resolvedFields.put(resolvedFieldName, weight);
-                    }
-                } else {
-                    resolvedFields.put(fieldName, weight);
-                }
+            if (Regex.isMatchAllPattern(defaultField)) {
+                queryParser = new QueryStringQueryParser(context, lenient == null ? true : lenient);
+            } else {
+                queryParser = new QueryStringQueryParser(context, defaultField, isLenient);
             }
+        } else if (fieldsAndWeights.size() > 0) {
+            final Map<String, Float> resolvedFields = QueryStringQueryParser.resolveMappingFields(context, fieldsAndWeights);
             queryParser = new QueryStringQueryParser(context, resolvedFields, isLenient);
         } else {
-            // If explicitly required to use all fields, use all fields, OR:
-            // Automatically determine the fields (to replace the _all field) if all of the following are true:
-            // - The _all field is disabled,
-            // - and the default_field has not been changed in the settings
-            // - and default_field is not specified in the request
-            // - and no fields are specified in the request
-            if ((useAllFields != null && useAllFields) ||
+            // Expand to all fields if:
+            // - The index default search field is "*"
+            // - The index default search field is "_all" and _all is disabled
+            // TODO the index default search field should be "*" for new indices.
+            if (Regex.isMatchAllPattern(context.defaultField()) ||
                     (context.getMapperService().allEnabled() == false && "_all".equals(context.defaultField()))) {
                 // Automatically determine the fields from the index mapping.
                 // Automatically set leniency to "true" if unset so mismatched fields don't cause exceptions;
-                queryParser = new QueryStringQueryParser(context, allQueryableDefaultFields(context), lenient == null ? true : lenient);
+                queryParser = new QueryStringQueryParser(context, lenient == null ? true : lenient);
             } else {
                 queryParser = new QueryStringQueryParser(context, context.defaultField(), isLenient);
             }

core/src/main/java/org/elasticsearch/index/query/SimpleQueryStringBuilder.java

@@ -33,6 +33,7 @@ import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.index.query.SimpleQueryParser.Settings;
+import org.elasticsearch.index.search.QueryStringQueryParser;
 
 import java.io.IOException;
 import java.util.HashMap;
@@ -376,7 +377,8 @@ public class SimpleQueryStringBuilder extends AbstractQueryBuilder<SimpleQuerySt
                 (context.getMapperService().allEnabled() == false &&
                         "_all".equals(context.defaultField()) &&
                         this.fieldsAndWeights.isEmpty())) {
-            resolvedFieldsAndWeights = QueryStringQueryBuilder.allQueryableDefaultFields(context);
+            resolvedFieldsAndWeights = QueryStringQueryParser.resolveMappingField(context, "*", 1.0f,
+                false, false);
             // Need to use lenient mode when using "all-mode" so exceptions aren't thrown due to mismatched types
             newSettings.lenient(lenientSet ? settings.lenient() : true);
         } else {

core/src/main/java/org/elasticsearch/index/search/ExistsFieldQueryExtension.java

@@ -1,44 +0,0 @@
-/*
- * Licensed to Elasticsearch under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-package org.elasticsearch.index.search;
-
-import org.apache.lucene.index.Term;
-import org.apache.lucene.search.Query;
-import org.apache.lucene.search.WildcardQuery;
-import org.elasticsearch.index.mapper.FieldNamesFieldMapper;
-import org.elasticsearch.index.query.ExistsQueryBuilder;
-import org.elasticsearch.index.query.QueryShardContext;
-
-public class ExistsFieldQueryExtension implements FieldQueryExtension {
-
-    public static final String NAME = "_exists_";
-
-    @Override
-    public Query query(QueryShardContext context, String queryText) {
-        final FieldNamesFieldMapper.FieldNamesFieldType fieldNamesFieldType =
-            (FieldNamesFieldMapper.FieldNamesFieldType) context.getMapperService().fullName(FieldNamesFieldMapper.NAME);
-        if (fieldNamesFieldType.isEnabled() == false) {
-            // The field_names_field is disabled so we switch to a wildcard query that matches all terms
-            return new WildcardQuery(new Term(queryText, "*"));
-        }
-
-        return ExistsQueryBuilder.newFilter(context, queryText);
-    }
-}

core/src/main/java/org/elasticsearch/index/search/FieldQueryExtension.java

@@ -1,28 +0,0 @@
-/*
- * Licensed to Elasticsearch under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-package org.elasticsearch.index.search;
-
-import org.apache.lucene.search.Query;
-import org.elasticsearch.index.query.QueryShardContext;
-
-public interface FieldQueryExtension {
-
-    Query query(QueryShardContext context, String queryText);
-}

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

@@ -29,6 +29,7 @@ import org.apache.lucene.search.BooleanClause.Occur;
 import org.apache.lucene.search.BooleanQuery;
 import org.apache.lucene.search.BoostQuery;
 import org.apache.lucene.search.FuzzyQuery;
+import org.apache.lucene.search.MatchNoDocsQuery;
 import org.apache.lucene.search.MultiPhraseQuery;
 import org.apache.lucene.search.MultiTermQuery;
 import org.apache.lucene.search.PhraseQuery;
@@ -41,9 +42,9 @@ 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.search.spans.SpanTermQuery;
+import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.QueryBuilder;
 import org.elasticsearch.ElasticsearchException;
-import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
@@ -58,6 +59,9 @@ import org.elasticsearch.index.query.support.QueryParsers;
 
 import java.io.IOException;
 
+import static org.elasticsearch.common.lucene.search.Queries.newLenientFieldQuery;
+import static org.elasticsearch.common.lucene.search.Queries.newUnmappedFieldQuery;
+
 public class MatchQuery {
 
     public enum Type implements Writeable {
@@ -224,23 +228,18 @@ public class MatchQuery {
 
     protected Analyzer getAnalyzer(MappedFieldType fieldType, boolean quoted) {
         if (analyzer == null) {
-            if (fieldType != null) {
-                return quoted ? context.getSearchQuoteAnalyzer(fieldType) : context.getSearchAnalyzer(fieldType);
-            }
-            return quoted ? context.getMapperService().searchQuoteAnalyzer() : context.getMapperService().searchAnalyzer();
+            return quoted ? context.getSearchQuoteAnalyzer(fieldType) : context.getSearchAnalyzer(fieldType);
         } else {
             return analyzer;
         }
     }
 
     public Query parse(Type type, String fieldName, Object value) throws IOException {
-        final String field;
         MappedFieldType fieldType = context.fieldMapper(fieldName);
-        if (fieldType != null) {
-            field = fieldType.name();
-        } else {
-            field = fieldName;
+        if (fieldType == null) {
+            return newUnmappedFieldQuery(fieldName);
         }
+        final String field = fieldType.name();
 
         /*
          * If the user forced an analyzer we really don't care if they are
@@ -251,7 +250,7 @@ public class MatchQuery {
          * passing through QueryBuilder.
          */
         boolean noForcedAnalyzer = this.analyzer == null;
-        if (fieldType != null && fieldType.tokenized() == false && noForcedAnalyzer) {
+        if (fieldType.tokenized() == false && noForcedAnalyzer) {
             return blendTermQuery(new Term(fieldName, value.toString()), fieldType);
         }
 
@@ -286,12 +285,12 @@ public class MatchQuery {
         }
     }
 
-    protected final Query termQuery(MappedFieldType fieldType, Object value, boolean lenient) {
+    protected final Query termQuery(MappedFieldType fieldType, BytesRef value, boolean lenient) {
         try {
             return fieldType.termQuery(value, context);
         } catch (RuntimeException e) {
             if (lenient) {
-                return null;
+                return newLenientFieldQuery(fieldType.name(), e);
             }
             throw e;
         }
@@ -311,7 +310,7 @@ public class MatchQuery {
         /**
          * Creates a new QueryBuilder using the given analyzer.
          */
-        MatchQueryBuilder(Analyzer analyzer, @Nullable MappedFieldType mapper) {
+        MatchQueryBuilder(Analyzer analyzer, MappedFieldType mapper) {
             super(analyzer);
             this.mapper = mapper;
         }
@@ -454,30 +453,21 @@ public class MatchQuery {
 
     protected Query blendTermQuery(Term term, MappedFieldType fieldType) {
         if (fuzziness != null) {
-            if (fieldType != null) {
-                try {
-                    Query query = fieldType.fuzzyQuery(term.text(), fuzziness, fuzzyPrefixLength, maxExpansions, transpositions);
-                    if (query instanceof FuzzyQuery) {
-                        QueryParsers.setRewriteMethod((FuzzyQuery) query, fuzzyRewriteMethod);
-                    }
-                    return query;
-                } catch (RuntimeException e) {
-                    if (lenient) {
-                        return null;
-                    } else {
-                        throw e;
-                    }
+            try {
+                Query query = fieldType.fuzzyQuery(term.text(), fuzziness, fuzzyPrefixLength, maxExpansions, transpositions);
+                if (query instanceof FuzzyQuery) {
+                    QueryParsers.setRewriteMethod((FuzzyQuery) query, fuzzyRewriteMethod);
+                }
+                return query;
+            } catch (RuntimeException e) {
+                if (lenient) {
+                    return newLenientFieldQuery(fieldType.name(), e);
+                } else {
+                    throw e;
                 }
             }
-            int edits = fuzziness.asDistance(term.text());
-            FuzzyQuery query = new FuzzyQuery(term, edits, fuzzyPrefixLength, maxExpansions, transpositions);
-            QueryParsers.setRewriteMethod(query, fuzzyRewriteMethod);
-            return query;
-        }
-        if (fieldType != null) {
-            return termQuery(fieldType, term.bytes(), lenient);
         }
-        return new TermQuery(term);
+        return termQuery(fieldType, term.bytes(), lenient);
     }
 
 }

core/src/main/java/org/elasticsearch/index/search/MultiMatchQuery.java

@@ -139,7 +139,7 @@ public class MultiMatchQuery extends MatchQuery {
             return MultiMatchQuery.super.blendTermsQuery(terms, fieldType);
         }
 
-        public Query termQuery(MappedFieldType fieldType, Object value) {
+        public Query termQuery(MappedFieldType fieldType, BytesRef value) {
             return MultiMatchQuery.this.termQuery(fieldType, value, lenient);
         }
     }
@@ -154,7 +154,7 @@ public class MultiMatchQuery extends MatchQuery {
         @Override
         public List<Query> buildGroupedQueries(MultiMatchQueryBuilder.Type type, Map<String, Float> fieldNames, Object value, String minimumShouldMatch) throws IOException {
             Map<Analyzer, List<FieldAndFieldType>> groups = new HashMap<>();
-            List<Tuple<String, Float>> missing = new ArrayList<>();
+            List<Query> queries = new ArrayList<>();
             for (Map.Entry<String, Float> entry : fieldNames.entrySet()) {
                 String name = entry.getKey();
                 MappedFieldType fieldType = context.fieldMapper(name);
@@ -168,15 +168,7 @@ public class MultiMatchQuery extends MatchQuery {
                     boost = boost == null ? Float.valueOf(1.0f) : boost;
                     groups.get(actualAnalyzer).add(new FieldAndFieldType(fieldType, boost));
                 } else {
-                    missing.add(new Tuple<>(name, entry.getValue()));
-                }
-
-            }
-            List<Query> queries = new ArrayList<>();
-            for (Tuple<String, Float> tuple : missing) {
-                Query q = parseGroup(type.matchQueryType(), tuple.v1(), tuple.v2(), value, minimumShouldMatch);
-                if (q != null) {
-                    queries.add(q);
+                    queries.add(new MatchNoDocsQuery("unknown field " + name));
                 }
             }
             for (List<FieldAndFieldType> group : groups.values()) {
@@ -225,13 +217,13 @@ public class MultiMatchQuery extends MatchQuery {
         }
 
         @Override
-        public Query termQuery(MappedFieldType fieldType, Object value) {
+        public Query termQuery(MappedFieldType fieldType, BytesRef value) {
             /*
              * Use the string value of the term because we're reusing the
              * portion of the query is usually after the analyzer has run on
              * each term. We just skip that analyzer phase.
              */
-            return blendTerm(new Term(fieldType.name(), value.toString()), fieldType);
+            return blendTerm(new Term(fieldType.name(), value.utf8ToString()), fieldType);
         }
     }
 
@@ -241,7 +233,7 @@ public class MultiMatchQuery extends MatchQuery {
     }
 
     static Query blendTerms(QueryShardContext context, BytesRef[] values, Float commonTermsCutoff, float tieBreaker,
-            FieldAndFieldType... blendedFields) {
+                            FieldAndFieldType... blendedFields) {
         List<Query> queries = new ArrayList<>();
         Term[] terms = new Term[blendedFields.length * values.length];
         float[] blendedBoost = new float[blendedFields.length * values.length];

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

@@ -38,19 +38,31 @@ import org.apache.lucene.search.MultiTermQuery;
 import org.apache.lucene.search.PhraseQuery;
 import org.apache.lucene.search.Query;
 import org.apache.lucene.search.SynonymQuery;
+import org.apache.lucene.search.WildcardQuery;
 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.apache.lucene.util.IOUtils;
 import org.elasticsearch.common.lucene.search.Queries;
+import org.elasticsearch.common.regex.Regex;
 import org.elasticsearch.common.unit.Fuzziness;
 import org.elasticsearch.index.analysis.ShingleTokenFilterFactory;
 import org.elasticsearch.index.mapper.AllFieldMapper;
 import org.elasticsearch.index.mapper.DateFieldMapper;
+import org.elasticsearch.index.mapper.DocumentMapper;
+import org.elasticsearch.index.mapper.FieldMapper;
+import org.elasticsearch.index.mapper.FieldNamesFieldMapper;
+import org.elasticsearch.index.mapper.IpFieldMapper;
+import org.elasticsearch.index.mapper.KeywordFieldMapper;
 import org.elasticsearch.index.mapper.MappedFieldType;
+import org.elasticsearch.index.mapper.MetadataFieldMapper;
+import org.elasticsearch.index.mapper.NumberFieldMapper;
+import org.elasticsearch.index.mapper.ScaledFloatFieldMapper;
 import org.elasticsearch.index.mapper.StringFieldType;
 import org.elasticsearch.index.mapper.MapperService;
+import org.elasticsearch.index.mapper.TextFieldMapper;
+import org.elasticsearch.index.query.ExistsQueryBuilder;
 import org.elasticsearch.index.query.MultiMatchQueryBuilder;
 import org.elasticsearch.index.query.QueryShardContext;
 import org.elasticsearch.index.query.support.QueryParsers;
@@ -61,11 +73,14 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
-import static java.util.Collections.unmodifiableMap;
 import static org.elasticsearch.common.lucene.search.Queries.fixNegativeQueryIfNeeded;
+import static org.elasticsearch.common.lucene.search.Queries.newLenientFieldQuery;
+import static org.elasticsearch.common.lucene.search.Queries.newUnmappedFieldQuery;
 
 /**
  * A {@link XQueryParser} that uses the {@link MapperService} in order to build smarter
@@ -74,12 +89,20 @@ import static org.elasticsearch.common.lucene.search.Queries.fixNegativeQueryIfN
  * to assemble the result logically.
  */
 public class QueryStringQueryParser extends XQueryParser {
-    private static final Map<String, FieldQueryExtension> FIELD_QUERY_EXTENSIONS;
+    // Mapping types the "all-ish" query can be executed against
+    private static final Set<String> ALLOWED_QUERY_MAPPER_TYPES;
+    private static final String EXISTS_FIELD = "_exists_";
 
     static {
-        Map<String, FieldQueryExtension> fieldQueryExtensions = new HashMap<>();
-        fieldQueryExtensions.put(ExistsFieldQueryExtension.NAME, new ExistsFieldQueryExtension());
-        FIELD_QUERY_EXTENSIONS = unmodifiableMap(fieldQueryExtensions);
+        ALLOWED_QUERY_MAPPER_TYPES = new HashSet<>();
+        ALLOWED_QUERY_MAPPER_TYPES.add(DateFieldMapper.CONTENT_TYPE);
+        ALLOWED_QUERY_MAPPER_TYPES.add(IpFieldMapper.CONTENT_TYPE);
+        ALLOWED_QUERY_MAPPER_TYPES.add(KeywordFieldMapper.CONTENT_TYPE);
+        for (NumberFieldMapper.NumberType nt : NumberFieldMapper.NumberType.values()) {
+            ALLOWED_QUERY_MAPPER_TYPES.add(nt.typeName());
+        }
+        ALLOWED_QUERY_MAPPER_TYPES.add(ScaledFloatFieldMapper.CONTENT_TYPE);
+        ALLOWED_QUERY_MAPPER_TYPES.add(TextFieldMapper.CONTENT_TYPE);
     }
 
     private final QueryShardContext context;
@@ -134,7 +157,18 @@ public class QueryStringQueryParser extends XQueryParser {
         this(context, null, fieldsAndWeights, lenient, context.getMapperService().searchAnalyzer());
     }
 
-    private QueryStringQueryParser(QueryShardContext context, String defaultField, Map<String, Float> fieldsAndWeights,
+    /**
+     * Defaults to all queryiable fields extracted from the mapping for query terms
+     * @param context The query shard context
+     * @param lenient If set to `true` will cause format based failures (like providing text to a numeric field) to be ignored.
+     */
+    public QueryStringQueryParser(QueryShardContext context, boolean lenient) {
+        this(context, "*", resolveMappingField(context, "*", 1.0f, false, false),
+                lenient, context.getMapperService().searchAnalyzer());
+    }
+
+    private QueryStringQueryParser(QueryShardContext context, String defaultField,
+                                   Map<String, Float> fieldsAndWeights,
                                    boolean lenient, Analyzer analyzer) {
         super(defaultField, analyzer);
         this.context = context;
@@ -144,6 +178,69 @@ public class QueryStringQueryParser extends XQueryParser {
         this.lenient = lenient;
     }
 
+
+    private static FieldMapper getFieldMapper(MapperService mapperService, String field) {
+        for (DocumentMapper mapper : mapperService.docMappers(true)) {
+            FieldMapper fieldMapper = mapper.mappers().smartNameFieldMapper(field);
+            if (fieldMapper != null) {
+                return fieldMapper;
+            }
+        }
+        return null;
+    }
+
+    public static Map<String, Float> resolveMappingFields(QueryShardContext context, Map<String, Float> fieldsAndWeights) {
+        Map<String, Float> resolvedFields = new HashMap<>();
+        for (Map.Entry<String, Float> fieldEntry : fieldsAndWeights.entrySet()) {
+            boolean allField = Regex.isMatchAllPattern(fieldEntry.getKey());
+            boolean multiField = Regex.isSimpleMatchPattern(fieldEntry.getKey());
+            float weight = fieldEntry.getValue() == null ? 1.0f : fieldEntry.getValue();
+            Map<String, Float> fieldMap = resolveMappingField(context, fieldEntry.getKey(), weight,  !multiField, !allField);
+            resolvedFields.putAll(fieldMap);
+        }
+        return resolvedFields;
+    }
+
+    public static Map<String, Float> resolveMappingField(QueryShardContext context, String field, float weight,
+                                                         boolean acceptMetadataField, boolean acceptAllTypes) {
+        return resolveMappingField(context, field, weight, acceptMetadataField, acceptAllTypes, false, null);
+    }
+
+    /**
+     * Given a shard context, return a map of all fields in the mappings that
+     * can be queried. The map will be field name to a float of 1.0f.
+     */
+    private static Map<String, Float> resolveMappingField(QueryShardContext context, String field, float weight,
+                                                          boolean acceptAllTypes, boolean acceptMetadataField,
+                                                          boolean quoted, String quoteFieldSuffix) {
+        Collection<String> allFields = context.simpleMatchToIndexNames(field);
+        Map<String, Float> fields = new HashMap<>();
+        for (String fieldName : allFields) {
+            if (quoted && quoteFieldSuffix != null && context.fieldMapper(fieldName + quoteFieldSuffix) != null) {
+                fieldName = fieldName + quoteFieldSuffix;
+            }
+            FieldMapper mapper = getFieldMapper(context.getMapperService(), fieldName);
+            if (mapper == null) {
+                // Unmapped fields are not ignored
+                fields.put(field, weight);
+                continue;
+            }
+            if (acceptMetadataField == false && mapper instanceof MetadataFieldMapper) {
+                // Ignore metadata fields
+                continue;
+            }
+            // Ignore fields that are not in the allowed mapper types. Some
+            // types do not support term queries, and thus we cannot generate
+            // a special query for them.
+            String mappingType = mapper.fieldType().typeName();
+            if (acceptAllTypes == false && ALLOWED_QUERY_MAPPER_TYPES.contains(mappingType) == false) {
+                continue;
+            }
+            fields.put(fieldName, weight);
+        }
+        return fields;
+    }
+
     @Override
     public void setDefaultOperator(Operator op) {
         super.setDefaultOperator(op);
@@ -234,18 +331,15 @@ public class QueryStringQueryParser extends XQueryParser {
 
     private Map<String, Float> extractMultiFields(String field, boolean quoted) {
         if (field != null) {
-            Collection<String> fields = queryBuilder.context.simpleMatchToIndexNames(field);
-            Map<String, Float> weights = new HashMap<>();
-            for (String fieldName : fields) {
-                Float weight = fieldsAndWeights.get(fieldName);
-                if (quoted && quoteFieldSuffix != null
-                        && queryBuilder.context.fieldMapper(fieldName + quoteFieldSuffix) != null) {
-                    fieldName = fieldName + quoteFieldSuffix;
-                    weight = fieldsAndWeights.get(fieldName);
-                }
-                weights.put(fieldName, weight == null ? 1.0f : weight);
+            boolean allFields = Regex.isMatchAllPattern(field);
+            if (allFields && this.field != null && this.field.equals(field)) {
+                // "*" is the default field
+                return fieldsAndWeights;
             }
-            return weights;
+            boolean multiFields = Regex.isSimpleMatchPattern(field);
+            // Filters unsupported fields if a pattern is requested
+            // Filters metadata fields if all fields are requested
+            return resolveMappingField(context, field, 1.0f, !allFields, !multiFields, quoted, quoteFieldSuffix);
         } else {
             return fieldsAndWeights;
         }
@@ -269,14 +363,14 @@ public class QueryStringQueryParser extends XQueryParser {
 
     @Override
     public Query getFieldQuery(String field, String queryText, boolean quoted) throws ParseException {
-        FieldQueryExtension fieldQueryExtension = FIELD_QUERY_EXTENSIONS.get(field);
-        if (fieldQueryExtension != null) {
-            return fieldQueryExtension.query(queryBuilder.context, queryText);
-        }
         if (quoted) {
             return getFieldQuery(field, queryText, getPhraseSlop());
         }
 
+        if (field != null && EXISTS_FIELD.equals(field)) {
+            return existsQuery(queryText);
+        }
+
         // Detects additional operators '<', '<=', '>', '>=' to handle range query with one side unbounded.
         // It is required to use a prefix field operator to enable the detection since they are not treated
         // as logical operator by the query parser (e.g. age:>=10).
@@ -305,7 +399,7 @@ public class QueryStringQueryParser extends XQueryParser {
             // the requested fields do not match any field in the mapping
             // happens for wildcard fields only since we cannot expand to a valid field name
             // if there is no match in the mappings.
-            return new MatchNoDocsQuery("empty fields");
+            return newUnmappedFieldQuery(field);
         }
         Analyzer oldAnalyzer = queryBuilder.analyzer;
         try {
@@ -324,7 +418,7 @@ public class QueryStringQueryParser extends XQueryParser {
     protected Query getFieldQuery(String field, String queryText, int slop) throws ParseException {
         Map<String, Float> fields = extractMultiFields(field, true);
         if (fields.isEmpty()) {
-            return new MatchNoDocsQuery("empty fields");
+            return newUnmappedFieldQuery(field);
         }
         final Query query;
         Analyzer oldAnalyzer = queryBuilder.analyzer;
@@ -357,20 +451,18 @@ public class QueryStringQueryParser extends XQueryParser {
         }
 
         Map<String, Float> fields = extractMultiFields(field, false);
-        if (fields == null) {
-            return getRangeQuerySingle(field, part1, part2, startInclusive, endInclusive, queryBuilder.context);
+        if (fields.isEmpty()) {
+            return newUnmappedFieldQuery(field);
         }
 
         List<Query> queries = new ArrayList<>();
         for (Map.Entry<String, Float> entry : fields.entrySet()) {
             Query q = getRangeQuerySingle(entry.getKey(), part1, part2, startInclusive, endInclusive, context);
-            if (q != null) {
-                queries.add(applyBoost(q, entry.getValue()));
-            }
+            assert q != null;
+            queries.add(applyBoost(q, entry.getValue()));
         }
-        if (queries.size() == 0) {
-            return null;
-        } else if (queries.size() == 1) {
+
+        if (queries.size() == 1) {
             return queries.get(0);
         }
         float tiebreaker = groupTieBreaker == null ? type.tieBreaker() : groupTieBreaker;
@@ -380,28 +472,28 @@ public class QueryStringQueryParser extends XQueryParser {
     private Query getRangeQuerySingle(String field, String part1, String part2,
                                       boolean startInclusive, boolean endInclusive, QueryShardContext context) {
         currentFieldType = context.fieldMapper(field);
-        if (currentFieldType != null) {
-            try {
-                Analyzer normalizer = forceAnalyzer == null ? queryBuilder.context.getSearchAnalyzer(currentFieldType) : forceAnalyzer;
-                BytesRef part1Binary = part1 == null ? null : normalizer.normalize(field, part1);
-                BytesRef part2Binary = part2 == null ? null : normalizer.normalize(field, part2);
-                Query rangeQuery;
-                if (currentFieldType instanceof DateFieldMapper.DateFieldType && timeZone != null) {
-                    DateFieldMapper.DateFieldType dateFieldType = (DateFieldMapper.DateFieldType) this.currentFieldType;
-                    rangeQuery = dateFieldType.rangeQuery(part1Binary, part2Binary,
-                        startInclusive, endInclusive, timeZone, null, context);
-                } else {
-                    rangeQuery = currentFieldType.rangeQuery(part1Binary, part2Binary, startInclusive, endInclusive, context);
-                }
-                return rangeQuery;
-            } catch (RuntimeException e) {
-                if (lenient) {
-                    return null;
-                }
-                throw e;
+        if (currentFieldType == null) {
+            return newUnmappedFieldQuery(field);
+        }
+        try {
+            Analyzer normalizer = forceAnalyzer == null ? queryBuilder.context.getSearchAnalyzer(currentFieldType) : forceAnalyzer;
+            BytesRef part1Binary = part1 == null ? null : normalizer.normalize(field, part1);
+            BytesRef part2Binary = part2 == null ? null : normalizer.normalize(field, part2);
+            Query rangeQuery;
+            if (currentFieldType instanceof DateFieldMapper.DateFieldType && timeZone != null) {
+                DateFieldMapper.DateFieldType dateFieldType = (DateFieldMapper.DateFieldType) this.currentFieldType;
+                rangeQuery = dateFieldType.rangeQuery(part1Binary, part2Binary,
+                    startInclusive, endInclusive, timeZone, null, context);
+            } else {
+                rangeQuery = currentFieldType.rangeQuery(part1Binary, part2Binary, startInclusive, endInclusive, context);
             }
+            return rangeQuery;
+        } catch (RuntimeException e) {
+            if (lenient) {
+                return newLenientFieldQuery(field, e);
+            }
+            throw e;
         }
-        return newRangeQuery(field, part1, part2, startInclusive, endInclusive);
     }
 
     @Override
@@ -415,39 +507,40 @@ public class QueryStringQueryParser extends XQueryParser {
     @Override
     protected Query getFuzzyQuery(String field, String termStr, float minSimilarity) throws ParseException {
         Map<String, Float> fields = extractMultiFields(field, false);
-        float tiebreaker = groupTieBreaker == null ? type.tieBreaker() : groupTieBreaker;
+        if (fields.isEmpty()) {
+            return newUnmappedFieldQuery(field);
+        }
         List<Query> queries = new ArrayList<>();
         for (Map.Entry<String, Float> entry : fields.entrySet()) {
             Query q = getFuzzyQuerySingle(entry.getKey(), termStr, minSimilarity);
-            if (q != null) {
-                queries.add(applyBoost(q, entry.getValue()));
-            }
+            assert q != null;
+            queries.add(applyBoost(q, entry.getValue()));
         }
-        if (queries.size() == 0) {
-            return null;
-        } else if (queries.size() == 1) {
+
+        if (queries.size() == 1) {
             return queries.get(0);
         } else {
+            float tiebreaker = groupTieBreaker == null ? type.tieBreaker() : groupTieBreaker;
             return new DisjunctionMaxQuery(queries, tiebreaker);
         }
     }
 
     private Query getFuzzyQuerySingle(String field, String termStr, float minSimilarity) throws ParseException {
         currentFieldType = context.fieldMapper(field);
-        if (currentFieldType != null) {
-            try {
-                Analyzer normalizer = forceAnalyzer == null ? queryBuilder.context.getSearchAnalyzer(currentFieldType) : forceAnalyzer;
-                BytesRef term = termStr == null ? null : normalizer.normalize(field, termStr);
-                return currentFieldType.fuzzyQuery(term, Fuzziness.fromEdits((int) minSimilarity),
-                    getFuzzyPrefixLength(), fuzzyMaxExpansions, FuzzyQuery.defaultTranspositions);
-            } catch (RuntimeException e) {
-                if (lenient) {
-                    return null;
-                }
-                throw e;
+        if (currentFieldType == null) {
+            return newUnmappedFieldQuery(field);
+        }
+        try {
+            Analyzer normalizer = forceAnalyzer == null ? queryBuilder.context.getSearchAnalyzer(currentFieldType) : forceAnalyzer;
+            BytesRef term = termStr == null ? null : normalizer.normalize(field, termStr);
+            return currentFieldType.fuzzyQuery(term, Fuzziness.fromEdits((int) minSimilarity),
+                getFuzzyPrefixLength(), fuzzyMaxExpansions, FuzzyQuery.defaultTranspositions);
+        } catch (RuntimeException e) {
+            if (lenient) {
+                return newLenientFieldQuery(field, e);
             }
+            throw e;
         }
-        return super.getFuzzyQuery(field, termStr, minSimilarity);
     }
 
     @Override
@@ -462,24 +555,20 @@ public class QueryStringQueryParser extends XQueryParser {
     @Override
     protected Query getPrefixQuery(String field, String termStr) throws ParseException {
         Map<String, Float> fields = extractMultiFields(field, false);
-        if (fields != null) {
-            float tiebreaker = groupTieBreaker == null ? type.tieBreaker() : groupTieBreaker;
-            List<Query> queries = new ArrayList<>();
-            for (Map.Entry<String, Float> entry : fields.entrySet()) {
-                Query q = getPrefixQuerySingle(entry.getKey(), termStr);
-                if (q != null) {
-                    queries.add(applyBoost(q, entry.getValue()));
-                }
-            }
-            if (queries.size() == 0) {
-                return null;
-            } else if (queries.size() == 1) {
-                return queries.get(0);
-            } else {
-                return new DisjunctionMaxQuery(queries, tiebreaker);
-            }
+        if (fields.isEmpty()) {
+            return newUnmappedFieldQuery(termStr);
+        }
+        List<Query> queries = new ArrayList<>();
+        for (Map.Entry<String, Float> entry : fields.entrySet()) {
+            Query q = getPrefixQuerySingle(entry.getKey(), termStr);
+            assert q != null;
+            queries.add(applyBoost(q, entry.getValue()));
+        }
+        if (queries.size() == 1) {
+            return queries.get(0);
         } else {
-            return getPrefixQuerySingle(field, termStr);
+            float tiebreaker = groupTieBreaker == null ? type.tieBreaker() : groupTieBreaker;
+            return new DisjunctionMaxQuery(queries, tiebreaker);
         }
     }
 
@@ -502,7 +591,7 @@ public class QueryStringQueryParser extends XQueryParser {
             return getPossiblyAnalyzedPrefixQuery(field, termStr);
         } catch (RuntimeException e) {
             if (lenient) {
-                return null;
+                return newLenientFieldQuery(field, e);
             }
             throw e;
         } finally {
@@ -551,7 +640,7 @@ public class QueryStringQueryParser extends XQueryParser {
         }
 
         if (tlist.size() == 0) {
-            return null;
+            return new MatchNoDocsQuery("analysis was empty for " + field + ":" + termStr);
         }
 
         if (tlist.size() == 1 && tlist.get(0).size() == 1) {
@@ -591,6 +680,17 @@ public class QueryStringQueryParser extends XQueryParser {
         return getBooleanQuery(clauses);
     }
 
+    private Query existsQuery(String fieldName) {
+        final FieldNamesFieldMapper.FieldNamesFieldType fieldNamesFieldType =
+            (FieldNamesFieldMapper.FieldNamesFieldType) context.getMapperService().fullName(FieldNamesFieldMapper.NAME);
+        if (fieldNamesFieldType.isEnabled() == false) {
+            // The field_names_field is disabled so we switch to a wildcard query that matches all terms
+            return new WildcardQuery(new Term(fieldName, "*"));
+        }
+
+        return ExistsQueryBuilder.newFilter(context, fieldName);
+    }
+
     @Override
     protected Query getWildcardQuery(String field, String termStr) throws ParseException {
         if (termStr.equals("*") && field != null) {
@@ -598,7 +698,7 @@ public class QueryStringQueryParser extends XQueryParser {
              * We rewrite _all:* to a match all query.
              * TODO: We can remove this special case when _all is completely removed.
              */
-            if ("*".equals(field) || AllFieldMapper.NAME.equals(field)) {
+            if (Regex.isMatchAllPattern(field) || AllFieldMapper.NAME.equals(field)) {
                 return newMatchAllDocsQuery();
             }
             String actualField = field;
@@ -606,35 +706,31 @@ public class QueryStringQueryParser extends XQueryParser {
                 actualField = this.field;
             }
             // effectively, we check if a field exists or not
-            return FIELD_QUERY_EXTENSIONS.get(ExistsFieldQueryExtension.NAME).query(queryBuilder.context, actualField);
+            return existsQuery(actualField);
         }
 
         Map<String, Float> fields = extractMultiFields(field, false);
-        if (fields != null) {
-            float tiebreaker = groupTieBreaker == null ? type.tieBreaker() : groupTieBreaker;
-            List<Query> queries = new ArrayList<>();
-            for (Map.Entry<String, Float> entry : fields.entrySet()) {
-                Query q = getWildcardQuerySingle(entry.getKey(), termStr);
-                if (q != null) {
-                    queries.add(applyBoost(q, entry.getValue()));
-                }
-            }
-            if (queries.size() == 0) {
-                return null;
-            } else if (queries.size() == 1) {
-                return queries.get(0);
-            } else {
-                return new DisjunctionMaxQuery(queries, tiebreaker);
-            }
+        if (fields.isEmpty()) {
+            return newUnmappedFieldQuery(termStr);
+        }
+        List<Query> queries = new ArrayList<>();
+        for (Map.Entry<String, Float> entry : fields.entrySet()) {
+            Query q = getWildcardQuerySingle(entry.getKey(), termStr);
+            assert q != null;
+            queries.add(applyBoost(q, entry.getValue()));
+        }
+        if (queries.size() == 1) {
+            return queries.get(0);
         } else {
-            return getWildcardQuerySingle(field, termStr);
+            float tiebreaker = groupTieBreaker == null ? type.tieBreaker() : groupTieBreaker;
+            return new DisjunctionMaxQuery(queries, tiebreaker);
         }
     }
 
     private Query getWildcardQuerySingle(String field, String termStr) throws ParseException {
         if ("*".equals(termStr)) {
             // effectively, we check if a field exists or not
-            return FIELD_QUERY_EXTENSIONS.get(ExistsFieldQueryExtension.NAME).query(queryBuilder.context, field);
+            return existsQuery(field);
         }
         String indexedNameField = field;
         currentFieldType = null;
@@ -648,7 +744,7 @@ public class QueryStringQueryParser extends XQueryParser {
             return super.getWildcardQuery(indexedNameField, termStr);
         } catch (RuntimeException e) {
             if (lenient) {
-                return null;
+                return newLenientFieldQuery(field, e);
             }
             throw e;
         } finally {
@@ -659,24 +755,20 @@ public class QueryStringQueryParser extends XQueryParser {
     @Override
     protected Query getRegexpQuery(String field, String termStr) throws ParseException {
         Map<String, Float> fields = extractMultiFields(field, false);
-        if (fields != null) {
-            float tiebreaker = groupTieBreaker == null ? type.tieBreaker() : groupTieBreaker;
-            List<Query> queries = new ArrayList<>();
-            for (Map.Entry<String, Float> entry : fields.entrySet()) {
-                Query q = getRegexpQuerySingle(entry.getKey(), termStr);
-                if (q != null) {
-                    queries.add(applyBoost(q, entry.getValue()));
-                }
-            }
-            if (queries.size() == 0) {
-                return null;
-            } else if (queries.size() == 1) {
-                return queries.get(0);
-            } else {
-                return new DisjunctionMaxQuery(queries, tiebreaker);
-            }
+        if (fields.isEmpty()) {
+            return newUnmappedFieldQuery(termStr);
+        }
+        List<Query> queries = new ArrayList<>();
+        for (Map.Entry<String, Float> entry : fields.entrySet()) {
+            Query q = getRegexpQuerySingle(entry.getKey(), termStr);
+            assert q != null;
+            queries.add(applyBoost(q, entry.getValue()));
+        }
+        if (queries.size() == 1) {
+            return queries.get(0);
         } else {
-            return getRegexpQuerySingle(field, termStr);
+            float tiebreaker = groupTieBreaker == null ? type.tieBreaker() : groupTieBreaker;
+            return new DisjunctionMaxQuery(queries, tiebreaker);
         }
     }
 
@@ -693,7 +785,7 @@ public class QueryStringQueryParser extends XQueryParser {
             return super.getRegexpQuery(field, termStr);
         } catch (RuntimeException e) {
             if (lenient) {
-                return null;
+                return newLenientFieldQuery(field, e);
             }
             throw e;
         } finally {

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

@@ -215,14 +215,14 @@ public class MultiMatchQueryBuilderTests extends AbstractQueryTestCase<MultiMatc
         DisjunctionMaxQuery dQuery = (DisjunctionMaxQuery) query;
         assertThat(dQuery.getTieBreakerMultiplier(), equalTo(1.0f));
         assertThat(dQuery.getDisjuncts().size(), equalTo(2));
-        assertThat(assertDisjunctionSubQuery(query, TermQuery.class, 0).getTerm(), equalTo(new Term(STRING_FIELD_NAME, "test")));
-        assertThat(assertDisjunctionSubQuery(query, TermQuery.class, 1).getTerm(), equalTo(new Term(STRING_FIELD_NAME_2, "test")));
+        assertThat(assertDisjunctionSubQuery(query, TermQuery.class, 0).getTerm(), equalTo(new Term(STRING_FIELD_NAME_2, "test")));
+        assertThat(assertDisjunctionSubQuery(query, TermQuery.class, 1).getTerm(), equalTo(new Term(STRING_FIELD_NAME, "test")));
     }
 
     public void testToQueryFieldMissing() throws Exception {
         assumeTrue("test runs only when at least a type is registered", getCurrentTypes().length > 0);
         assertThat(multiMatchQuery("test").field(MISSING_WILDCARD_FIELD_NAME).toQuery(createShardContext()), instanceOf(MatchNoDocsQuery.class));
-        assertThat(multiMatchQuery("test").field(MISSING_FIELD_NAME).toQuery(createShardContext()), instanceOf(TermQuery.class));
+        assertThat(multiMatchQuery("test").field(MISSING_FIELD_NAME).toQuery(createShardContext()), instanceOf(MatchNoDocsQuery.class));
     }
 
     public void testFromJson() throws IOException {

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

@@ -167,14 +167,11 @@ public class QueryStringQueryBuilderTests extends AbstractQueryTestCase<QueryStr
     @Override
     protected void doAssertLuceneQuery(QueryStringQueryBuilder queryBuilder,
                                        Query query, SearchContext context) throws IOException {
-        if ("".equals(queryBuilder.queryString())) {
-            assertThat(query, instanceOf(MatchNoDocsQuery.class));
-        } else {
-            assertThat(query, either(instanceOf(TermQuery.class)).or(instanceOf(AllTermQuery.class))
-                    .or(instanceOf(BooleanQuery.class)).or(instanceOf(DisjunctionMaxQuery.class))
-                    .or(instanceOf(PhraseQuery.class)).or(instanceOf(BoostQuery.class))
-                    .or(instanceOf(MultiPhrasePrefixQuery.class)).or(instanceOf(PrefixQuery.class)).or(instanceOf(SpanQuery.class)));
-        }
+        assertThat(query, either(instanceOf(TermQuery.class)).or(instanceOf(AllTermQuery.class))
+            .or(instanceOf(BooleanQuery.class)).or(instanceOf(DisjunctionMaxQuery.class))
+            .or(instanceOf(PhraseQuery.class)).or(instanceOf(BoostQuery.class))
+            .or(instanceOf(MultiPhrasePrefixQuery.class)).or(instanceOf(PrefixQuery.class)).or(instanceOf(SpanQuery.class))
+            .or(instanceOf(MatchNoDocsQuery.class)));
     }
 
     public void testIllegalArguments() {
@@ -293,9 +290,9 @@ public class QueryStringQueryBuilderTests extends AbstractQueryTestCase<QueryStr
         DisjunctionMaxQuery dQuery = (DisjunctionMaxQuery) query;
         assertThat(dQuery.getDisjuncts().size(), equalTo(2));
         assertThat(assertDisjunctionSubQuery(query, TermQuery.class, 0).getTerm(),
-            equalTo(new Term(STRING_FIELD_NAME, "test")));
-        assertThat(assertDisjunctionSubQuery(query, TermQuery.class, 1).getTerm(),
             equalTo(new Term(STRING_FIELD_NAME_2, "test")));
+        assertThat(assertDisjunctionSubQuery(query, TermQuery.class, 1).getTerm(),
+            equalTo(new Term(STRING_FIELD_NAME, "test")));
     }
 
     public void testToQueryDisMaxQuery() throws Exception {
@@ -310,7 +307,7 @@ public class QueryStringQueryBuilderTests extends AbstractQueryTestCase<QueryStr
         assertTermOrBoostQuery(disjuncts.get(1), STRING_FIELD_NAME_2, "test", 1.0f);
     }
 
-    public void testToQueryWildcarQuery() throws Exception {
+    public void testToQueryWildcardQuery() throws Exception {
         assumeTrue("test runs only when at least a type is registered", getCurrentTypes().length > 0);
         for (Operator op : Operator.values()) {
             BooleanClause.Occur defaultOp = op.toBooleanClauseOccur();
@@ -676,10 +673,10 @@ public class QueryStringQueryBuilderTests extends AbstractQueryTestCase<QueryStr
         assertThat(expectedQuery, equalTo(query));
 
         queryStringQueryBuilder =
-            new QueryStringQueryBuilder("field:foo bar").field("invalid*");
+            new QueryStringQueryBuilder(STRING_FIELD_NAME + ":foo bar").field("invalid*");
         query = queryStringQueryBuilder.toQuery(createShardContext());
         expectedQuery = new BooleanQuery.Builder()
-            .add(new TermQuery(new Term("field", "foo")), Occur.SHOULD)
+            .add(new TermQuery(new Term(STRING_FIELD_NAME, "foo")), Occur.SHOULD)
             .add(new MatchNoDocsQuery("empty fields"), Occur.SHOULD)
             .build();
         assertThat(expectedQuery, equalTo(query));
@@ -783,8 +780,6 @@ public class QueryStringQueryBuilderTests extends AbstractQueryTestCase<QueryStr
 
     public void testExistsFieldQuery() throws Exception {
         assumeTrue("test runs only when at least a type is registered", getCurrentTypes().length > 0);
-        assumeTrue("5.x behaves differently, so skip on non-6.x indices",
-                indexVersionCreated.onOrAfter(Version.V_6_0_0_alpha1));
 
         QueryShardContext context = createShardContext();
         QueryStringQueryBuilder queryBuilder = new QueryStringQueryBuilder("foo:*");
@@ -804,11 +799,7 @@ public class QueryStringQueryBuilderTests extends AbstractQueryTestCase<QueryStr
 
         queryBuilder = new QueryStringQueryBuilder("*");
         query = queryBuilder.toQuery(context);
-        List<Query> fieldQueries = new ArrayList<> ();
-        for (String type : QueryStringQueryBuilder.allQueryableDefaultFields(context).keySet()) {
-            fieldQueries.add(new ConstantScoreQuery(new TermQuery(new Term("_field_names", type))));
-        }
-        expected = new DisjunctionMaxQuery(fieldQueries, 0f);
+        expected = new MatchAllDocsQuery();
         assertThat(query, equalTo(expected));
     }
 
@@ -863,6 +854,7 @@ public class QueryStringQueryBuilderTests extends AbstractQueryTestCase<QueryStr
     }
 
     public void testExpandedTerms() throws Exception {
+        assumeTrue("test runs only when at least a type is registered", getCurrentTypes().length > 0);
         // Prefix
         Query query = new QueryStringQueryBuilder("aBc*")
                 .field(STRING_FIELD_NAME)
@@ -914,31 +906,59 @@ public class QueryStringQueryBuilderTests extends AbstractQueryTestCase<QueryStr
         assertEquals(new TermRangeQuery(STRING_FIELD_NAME, new BytesRef("abc"), new BytesRef("bcd"), true, true), query);
     }
 
-    public void testAllFieldsWithFields() throws IOException {
-        String json =
-                "{\n" +
-                "  \"query_string\" : {\n" +
-                "    \"query\" : \"this AND that OR thus\",\n" +
-                "    \"fields\" : [\"foo\"],\n" +
-                "    \"all_fields\" : true\n" +
-                "  }\n" +
-                "}";
-
-        ParsingException e = expectThrows(ParsingException.class, () -> parseQuery(json));
+    public void testDefaultFieldsWithFields() throws IOException {
+        QueryShardContext context = createShardContext();
+        QueryStringQueryBuilder builder = new QueryStringQueryBuilder("aBc*")
+            .field("field")
+            .defaultField("*");
+        QueryValidationException e = expectThrows(QueryValidationException.class, () -> builder.toQuery(context));
         assertThat(e.getMessage(),
-                containsString("cannot use [all_fields] parameter in conjunction with [default_field] or [fields]"));
+            containsString("cannot use [fields] parameter in conjunction with [default_field]"));
+    }
 
-        String json2 =
-                "{\n" +
-                "  \"query_string\" : {\n" +
-                "    \"query\" : \"this AND that OR thus\",\n" +
-                "    \"default_field\" : \"foo\",\n" +
-                "    \"all_fields\" : true\n" +
-                "  }\n" +
-                "}";
+    public void testLenientRewriteToMatchNoDocs() throws IOException {
+        assumeTrue("test runs only when at least a type is registered", getCurrentTypes().length > 0);
+        // Term
+        Query query = new QueryStringQueryBuilder("hello")
+            .field(INT_FIELD_NAME)
+            .lenient(true)
+            .toQuery(createShardContext());
+        assertEquals(new MatchNoDocsQuery(""), query);
 
-        e = expectThrows(ParsingException.class, () -> parseQuery(json2));
-        assertThat(e.getMessage(),
-                containsString("cannot use [all_fields] parameter in conjunction with [default_field] or [fields]"));
+        // prefix
+        query = new QueryStringQueryBuilder("hello*")
+            .field(INT_FIELD_NAME)
+            .lenient(true)
+            .toQuery(createShardContext());
+        assertEquals(new MatchNoDocsQuery(""), query);
+
+        // Fuzzy
+        query = new QueryStringQueryBuilder("hello~2")
+            .field(INT_FIELD_NAME)
+            .lenient(true)
+            .toQuery(createShardContext());
+        assertEquals(new MatchNoDocsQuery(""), query);
+    }
+
+    public void testUnmappedFieldRewriteToMatchNoDocs() throws IOException {
+        // Default unmapped field
+        Query query = new QueryStringQueryBuilder("hello")
+            .field("unmapped_field")
+            .lenient(true)
+            .toQuery(createShardContext());
+        assertEquals(new MatchNoDocsQuery(""), query);
+
+        // Unmapped prefix field
+        query = new QueryStringQueryBuilder("unmapped_field:hello")
+            .lenient(true)
+            .toQuery(createShardContext());
+        assertEquals(new MatchNoDocsQuery(""), query);
+
+        // Unmapped fields
+        query = new QueryStringQueryBuilder("hello")
+            .lenient(true)
+            .field("unmapped_field")
+            .toQuery(createShardContext());
+        assertEquals(new MatchNoDocsQuery(""), query);
     }
 }

core/src/test/java/org/elasticsearch/index/search/MultiMatchQueryTests.java

@@ -27,6 +27,7 @@ import org.apache.lucene.search.BooleanQuery;
 import org.apache.lucene.search.BoostQuery;
 import org.apache.lucene.search.DisjunctionMaxQuery;
 import org.apache.lucene.search.MatchAllDocsQuery;
+import org.apache.lucene.search.MatchNoDocsQuery;
 import org.apache.lucene.search.Query;
 import org.apache.lucene.search.SynonymQuery;
 import org.apache.lucene.search.TermQuery;
@@ -97,8 +98,8 @@ public class MultiMatchQueryTests extends ESSingleNodeTestCase {
             Query tq2 = new BoostQuery(new TermQuery(new Term("name.last", "banon")), 3);
             Query expected = new DisjunctionMaxQuery(
                 Arrays.asList(
-                    new TermQuery(new Term("foobar", "banon")),
-                    new DisjunctionMaxQuery(Arrays.asList(tq1, tq2), 0f)
+                    new MatchNoDocsQuery("unknown field foobar"),
+                    new DisjunctionMaxQuery(Arrays.asList(tq2, tq1), 0f)
                 ), 0f);
             assertEquals(expected, rewrittenQuery);
         }

core/src/test/java/org/elasticsearch/search/query/QueryStringIT.java

@@ -207,31 +207,41 @@ public class QueryStringIT extends ESIntegTestCase {
         assertHitCount(resp, 3L);
     }
 
-    public void testExplicitAllFieldsRequested() throws Exception {
-        String indexBody = copyToStringFromClasspath("/org/elasticsearch/search/query/all-query-index-with-all.json");
-        prepareCreate("test2").setSource(indexBody, XContentType.JSON).get();
-        ensureGreen("test2");
+    public void testAllFields() throws Exception {
+        String indexBodyWithAll = copyToStringFromClasspath("/org/elasticsearch/search/query/all-query-index-with-all.json");
+        String indexBody = copyToStringFromClasspath("/org/elasticsearch/search/query/all-query-index.json");
+
+        // Defaults to index.query.default_field=_all
+        prepareCreate("test_1").setSource(indexBodyWithAll, XContentType.JSON).get();
+        Settings.Builder settings = Settings.builder().put("index.query.default_field", "*");
+        prepareCreate("test_2").setSource(indexBody, XContentType.JSON).setSettings(settings).get();
+        ensureGreen("test_1","test_2");
 
         List<IndexRequestBuilder> reqs = new ArrayList<>();
-        reqs.add(client().prepareIndex("test2", "doc", "1").setSource("f1", "foo", "f2", "eggplant"));
+        reqs.add(client().prepareIndex("test_1", "doc", "1").setSource("f1", "foo", "f2", "eggplant"));
+        reqs.add(client().prepareIndex("test_2", "doc", "1").setSource("f1", "foo", "f2", "eggplant"));
         indexRandom(true, false, reqs);
 
-        SearchResponse resp = client().prepareSearch("test2").setQuery(
-                queryStringQuery("foo eggplant").defaultOperator(Operator.AND)).get();
+        SearchResponse resp = client().prepareSearch("test_1").setQuery(
+            queryStringQuery("foo eggplant").defaultOperator(Operator.AND)).get();
         assertHitCount(resp, 0L);
 
-        resp = client().prepareSearch("test2").setQuery(
-                queryStringQuery("foo eggplant").defaultOperator(Operator.OR).useAllFields(true)).get();
+        resp = client().prepareSearch("test_2").setQuery(
+            queryStringQuery("foo eggplant").defaultOperator(Operator.AND)).get();
+        assertHitCount(resp, 0L);
+
+        resp = client().prepareSearch("test_1").setQuery(
+            queryStringQuery("foo eggplant").defaultOperator(Operator.OR)).get();
         assertHits(resp.getHits(), "1");
         assertHitCount(resp, 1L);
 
-        Exception e = expectThrows(Exception.class, () ->
-                client().prepareSearch("test2").setQuery(
-                        queryStringQuery("blah").field("f1").useAllFields(true)).get());
-        assertThat(ExceptionsHelper.detailedMessage(e),
-                containsString("cannot use [all_fields] parameter in conjunction with [default_field] or [fields]"));
+        resp = client().prepareSearch("test_2").setQuery(
+            queryStringQuery("foo eggplant").defaultOperator(Operator.OR)).get();
+        assertHits(resp.getHits(), "1");
+        assertHitCount(resp, 1L);
     }
 
+
     @LuceneTestCase.AwaitsFix(bugUrl="currently can't perform phrase queries on fields that don't support positions")
     public void testPhraseQueryOnFieldWithNoPositions() throws Exception {
         List<IndexRequestBuilder> reqs = new ArrayList<>();

core/src/test/java/org/elasticsearch/validate/SimpleValidateQueryIT.java

@@ -111,7 +111,7 @@ public class SimpleValidateQueryIT extends ESIntegTestCase {
                     .execute().actionGet();
             assertThat(response.isValid(), equalTo(true));
             assertThat(response.getQueryExplanation().size(), equalTo(1));
-            assertThat(response.getQueryExplanation().get(0).getExplanation(), equalTo("(foo:foo | baz:foo)"));
+            assertThat(response.getQueryExplanation().get(0).getExplanation(), equalTo("(MatchNoDocsQuery(\"failed [bar] query, caused by number_format_exception:[For input string: \"foo\"]\") | foo:foo | baz:foo)"));
             assertThat(response.getQueryExplanation().get(0).getError(), nullValue());
         }
     }

docs/reference/migration/migrate_6_0/search.asciidoc

@@ -68,6 +68,10 @@
   use an explicit quoted query instead.
   If provided, it will be ignored and issue a deprecation warning.
 
+* The `all_fields` parameter for the `query_string` has been removed.
+  Set `default_field` to *` instead.
+  If provided, `default_field` will be automatically set to `*`
+
 * The `index` parameter in the terms filter, used to look up terms in a dedicated index is
   now mandatory. Previously, the index defaulted to the index the query was executed on. Now this index
   must be explicitly set in the request.

docs/reference/query-dsl/query-string-query.asciidoc

@@ -50,7 +50,10 @@ The `query_string` top level parameters include:
 
 |`default_field` |The default field for query terms if no prefix field
 is specified. Defaults to the `index.query.default_field` index
-settings, which in turn defaults to `_all`.
+settings, which in turn defaults to `*`.
+`*` extracts all fields in the mapping that are eligible to term queries
+and filters the metadata fields. All extracted fields are then combined
+to build a query when no prefix field is provided.
 
 |`default_operator` |The default operator used if no explicit operator
 is specified. For example, with a default operator of `OR`, the query
@@ -107,7 +110,8 @@ the query string. This allows to use a field that has a different analysis chain
 for exact matching. Look <<mixing-exact-search-with-stemming,here>> for a
 comprehensive example.
 
-|`all_fields` | Perform the query on all fields detected in the mapping that can
+|`all_fields` | deprecated[6.0.0, set `default_field` to `*` instead]
+Perform the query on all fields detected in the mapping that can
 be queried. Will be used by default when the `_all` field is disabled and no
 `default_field` is specified (either in the index settings or in the request
 body) and no `fields` are specified.
@@ -124,11 +128,9 @@ parameter.
 
 When not explicitly specifying the field to search on in the query
 string syntax, the `index.query.default_field` will be used to derive
-which field to search on. It defaults to `_all` field.
-
-If the `_all` field is disabled, the `query_string` query will automatically
-attempt to determine the existing fields in the index's mapping that are
-queryable, and perform the search on those fields. Note that this will not
+which field to search on. If the `index.query.default_field` is not specified,
+the `query_string` will automatically attempt to determine the existing fields in the index's
+mapping that are queryable, and perform the search on those fields. Note that this will not
 include nested documents, use a nested query to search those documents.
 
 [float]