Deprecate negative field boosts in analyzed queries (elastic#38176)

This change forbids negative field boost in the `query_string`, `simple_query_string`
and `multi_match` queries.
Negative boosts are not allowed in Lucene 8 (scores must be positive).
The backport of this change to 6x will turn the error into a deprecation warning
in order to raise the awareness of this breaking change in 7.0.

Closes elastic#33309

docs/reference/migration/migrate_6_0/search.asciidoc

@@ -153,10 +153,10 @@ information.
 [float]
 ===== Negative scores are deprecated in Function Score Query
 
-Negative scores in the Function Score Query are deprecated. If a negative 
+Negative scores in the Function Score Query are deprecated. If a negative
 score is produced as a result of computation (e.g. in `script_score` or
 `field_value_factor` functions), a deprecation warning will be issued in
-this major version, and an error will be thrown in the next major version. 
+this major version, and an error will be thrown in the next major version.
 
 [float]
 ==== Fielddata on `_uid`
@@ -266,8 +266,8 @@ rewrite any prefix query on the field to a a single term query that matches the
 [float]
 ==== Negative boosts are deprecated
 
-Setting a negative `boost` in a query is deprecated and will throw an error in the next version.
-To deboost a specific query you can use a `boost` comprise between 0 and 1.
+Setting a negative `boost` for a query or a field is deprecated and will throw an error in the next
+major version. To deboost a specific query or field you can use a `boost` comprise between 0 and 1.
 
 [float]
 ==== Limit the number of open scroll contexts

server/src/main/java/org/elasticsearch/index/query/AbstractQueryBuilder.java

@@ -70,6 +70,7 @@ protected AbstractQueryBuilder() {
 
     protected AbstractQueryBuilder(StreamInput in) throws IOException {
         boost = in.readFloat();
+        checkNegativeBoost(boost);
         queryName = in.readOptionalString();
     }
 
@@ -158,17 +159,21 @@ public final float boost() {
         return this.boost;
     }
 
+    protected final void checkNegativeBoost(float boost) {
+        if (Float.compare(boost, 0f) < 0) {
+            deprecationLogger.deprecatedAndMaybeLog("negative boost", "setting a negative [boost] on a query " +
+                "is deprecated and will throw an error in the next major version. You can use a value between 0 and 1 to deboost.");
+        }
+    }
+
     /**
      * Sets the boost for this query.  Documents matching this query will (in addition to the normal
      * weightings) have their score multiplied by the boost provided.
      */
     @SuppressWarnings("unchecked")
     @Override
     public final QB boost(float boost) {
-        if (Float.compare(boost, 0f) < 0) {
-            deprecationLogger.deprecatedAndMaybeLog("negative boost", "setting a negative [boost] on a query " +
-                "is deprecated and will throw an error in the next version. You can use a value between 0 and 1 to deboost.");
-        }
+        checkNegativeBoost(boost);
         this.boost = boost;
         return (QB) this;
     }

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

@@ -213,7 +213,10 @@ public MultiMatchQueryBuilder(StreamInput in) throws IOException {
         int size = in.readVInt();
         fieldsBoosts = new TreeMap<>();
         for (int i = 0; i < size; i++) {
-            fieldsBoosts.put(in.readString(), in.readFloat());
+            String field = in.readString();
+            float boost = in.readFloat();
+            checkNegativeBoost(boost);
+            fieldsBoosts.put(field, boost);
         }
         type = Type.readFromStream(in);
         operator = Operator.readFromStream(in);
@@ -293,6 +296,7 @@ public MultiMatchQueryBuilder field(String field, float boost) {
         if (Strings.isEmpty(field)) {
             throw new IllegalArgumentException("supplied field is null or empty.");
         }
+        checkNegativeBoost(boost);
         this.fieldsBoosts.put(field, boost);
         return this;
     }
@@ -301,6 +305,9 @@ public MultiMatchQueryBuilder field(String field, float boost) {
      * Add several fields to run the query against with a specific boost.
      */
     public MultiMatchQueryBuilder fields(Map<String, Float> fields) {
+        for (float fieldBoost : fields.values()) {
+            checkNegativeBoost(fieldBoost);
+        }
         this.fieldsBoosts.putAll(fields);
         return this;
     }

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

@@ -184,7 +184,10 @@ public QueryStringQueryBuilder(StreamInput in) throws IOException {
         defaultField = in.readOptionalString();
         int size = in.readVInt();
         for (int i = 0; i < size; i++) {
-            fieldsAndWeights.put(in.readString(), in.readFloat());
+            String field = in.readString();
+            Float weight = in.readFloat();
+            checkNegativeBoost(weight);
+            fieldsAndWeights.put(field, weight);
         }
         defaultOperator = Operator.readFromStream(in);
         analyzer = in.readOptionalString();
@@ -339,6 +342,7 @@ public QueryStringQueryBuilder field(String field) {
      * Adds a field to run the query string against with a specific boost.
      */
     public QueryStringQueryBuilder field(String field, float boost) {
+        checkNegativeBoost(boost);
         this.fieldsAndWeights.put(field, boost);
         return this;
     }
@@ -347,6 +351,9 @@ public QueryStringQueryBuilder field(String field, float boost) {
      * Add several fields to run the query against with a specific boost.
      */
     public QueryStringQueryBuilder fields(Map<String, Float> fields) {
+        for (float fieldBoost : fields.values()) {
+            checkNegativeBoost(fieldBoost);
+        }
         this.fieldsAndWeights.putAll(fields);
         return this;
     }

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

@@ -163,6 +163,7 @@ public SimpleQueryStringBuilder(StreamInput in) throws IOException {
         for (int i = 0; i < size; i++) {
             String field = in.readString();
             Float weight = in.readFloat();
+            checkNegativeBoost(weight);
             fields.put(field, weight);
         }
         fieldsAndWeights.putAll(fields);
@@ -258,13 +259,17 @@ public SimpleQueryStringBuilder field(String field, float boost) {
         if (Strings.isEmpty(field)) {
             throw new IllegalArgumentException("supplied field is null or empty");
         }
+        checkNegativeBoost(boost);
         this.fieldsAndWeights.put(field, boost);
         return this;
     }
 
     /** Add several fields to run the query against with a specific boost. */
     public SimpleQueryStringBuilder fields(Map<String, Float> fields) {
         Objects.requireNonNull(fields, "fields cannot be null");
+        for (float fieldBoost : fields.values()) {
+            checkNegativeBoost(fieldBoost);
+        }
         this.fieldsAndWeights.putAll(fields);
         return this;
     }

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

@@ -96,11 +96,10 @@ private List<Query> buildFieldQueries(MultiMatchQueryBuilder.Type type, Map<Stri
                 // ignore unmapped fields
                 continue;
             }
-            Float boostValue = fieldNames.get(fieldName);
+            float boostValue = fieldNames.getOrDefault(fieldName, 1.0f);
             Query query = parse(type.matchQueryType(), fieldName, value);
             query = Queries.maybeApplyMinimumShouldMatch(query, minimumShouldMatch);
             if (query != null
-                    && boostValue != null
                     && boostValue != AbstractQueryBuilder.DEFAULT_BOOST
                     && query instanceof MatchNoDocsQuery == false) {
                 query = new BoostQuery(query, boostValue);

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

@@ -485,7 +485,7 @@ public void testWithStopWords() throws Exception {
 
     public void testDisMaxDeprecation() throws Exception {
         String json =
-                "{\n" +
+            "{\n" +
                 "  \"multi_match\" : {\n" +
                 "    \"query\" : \"foo:bar\",\n" +
                 "    \"use_dis_max\" : true\n" +
@@ -496,6 +496,15 @@ public void testDisMaxDeprecation() throws Exception {
         assertWarnings("Deprecated field [use_dis_max] used, replaced by [use tie_breaker instead]");
     }
 
+    public void testNegativeFieldBoost() throws IOException {
+        Query query = new MultiMatchQueryBuilder("the quick fox")
+                .field(STRING_FIELD_NAME, -1.0f)
+                .field(STRING_FIELD_NAME_2)
+                .toQuery(createShardContext());
+        assertWarnings("setting a negative [boost] on a query is deprecated and will throw an error in the next major " +
+            "version. You can use a value between 0 and 1 to deboost.");
+    }
+
     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/QueryStringQueryBuilderTests.java

@@ -1488,6 +1488,15 @@ public void testAnalyzedPrefix() throws Exception {
         assertEquals(expected, query);
     }
 
+    public void testNegativeFieldBoost() throws IOException {
+        Query query =  new QueryStringQueryBuilder("the quick fox")
+            .field(STRING_FIELD_NAME, -1.0f)
+            .field(STRING_FIELD_NAME_2)
+            .toQuery(createShardContext());
+        assertWarnings("setting a negative [boost] on a query is deprecated and will throw an error in the next major " +
+            "version. You can use a value between 0 and 1 to deboost.");
+    }
+
     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

@@ -739,6 +739,15 @@ public void testUnmappedFieldNoTokenWithAndOperator() throws IOException {
         assertEquals(expected, query);
     }
 
+    public void testNegativeFieldBoost() throws IOException {
+        Query query =   new SimpleQueryStringBuilder("the quick fox")
+            .field(STRING_FIELD_NAME, -1.0f)
+            .field(STRING_FIELD_NAME_2)
+            .toQuery(createShardContext());
+        assertWarnings("setting a negative [boost] on a query is deprecated and will throw an error in the next major " +
+            "version. You can use a value between 0 and 1 to deboost.");
+    }
+
     private static IndexMetaData newIndexMeta(String name, Settings oldIndexSettings, Settings indexSettings) {
         Settings build = Settings.builder().put(oldIndexSettings)
             .put(indexSettings)

test/framework/src/main/java/org/elasticsearch/test/AbstractQueryTestCase.java

@@ -105,7 +105,7 @@ public void testNegativeBoosts() {
         QB testQuery = createTestQueryBuilder();
         testQuery.boost(-0.5f);
         assertWarnings("setting a negative [boost] on a query" +
-            " is deprecated and will throw an error in the next version. You can use a value between 0 and 1 to deboost.");
+            " is deprecated and will throw an error in the next major version. You can use a value between 0 and 1 to deboost.");
     }
 
     /**