More Like This: renamed ignore_like to unlike

This changes the parameter name `ignore_like` to the more user friendly name
`unlike`. This later feature generates a query from the terms in `A` but not
from the terms in `B`. This translates to a result set which is like `A` but
unlike `B`. We could have further negatively boosted any documents that have
some `B`, but these documents already do not receive any contribution from
having `B`, and would therefore negatively compete with documents having `A`.

Closes #11117

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

@@ -51,8 +51,8 @@ public class MoreLikeThisQuery extends Query {
 
     private String[] likeText;
     private Fields[] likeFields;
-    private String[] ignoreText;
+    private String[] unlikeText;
-    private Fields[] ignoreFields;
+    private Fields[] unlikeFields;
     private String[] moreLikeFields;
     private Analyzer analyzer;
     private String minimumShouldMatch = DEFAULT_MINIMUM_SHOULD_MATCH;
@@ -155,10 +155,14 @@ public class MoreLikeThisQuery extends Query {
         mlt.setBoost(boostTerms);
         mlt.setBoostFactor(boostTermsFactor);
 
-        if (this.ignoreText != null || this.ignoreFields != null) {
+        if (this.unlikeText != null || this.unlikeFields != null) {
-            handleSkipTerms(mlt, this.ignoreText, this.ignoreFields);
+            handleUnlike(mlt, this.unlikeText, this.unlikeFields);
         }
+        
+        return createQuery(mlt);
+    }
 
+    private Query createQuery(XMoreLikeThis mlt) throws IOException {
         BooleanQuery bq = new BooleanQuery();
         if (this.likeFields != null) {
             Query mltQuery = mlt.like(this.likeFields);
@@ -177,14 +181,14 @@ public class MoreLikeThisQuery extends Query {
         }
 
         bq.setBoost(getBoost());
-        return bq;
+        return bq;    
     }
 
-    private void handleSkipTerms(XMoreLikeThis mlt, String[] ignoreText, Fields[] ignoreFields) throws IOException {
+    private void handleUnlike(XMoreLikeThis mlt, String[] unlikeText, Fields[] unlikeFields) throws IOException {
         Set<Term> skipTerms = new HashSet<>();
         // handle like text
-        if (ignoreText != null) {
+        if (unlikeText != null) {
-            for (String text : ignoreText) {
+            for (String text : unlikeText) {
                 // only use the first field to be consistent
                 String fieldName = moreLikeFields[0];
                 try (TokenStream ts = analyzer.tokenStream(fieldName, text)) {
@@ -198,8 +202,8 @@ public class MoreLikeThisQuery extends Query {
             }
         }
         // handle like fields
-        if (ignoreFields != null) {
+        if (unlikeFields != null) {
-            for (Fields fields : ignoreFields) {
+            for (Fields fields : unlikeFields) {
                 for (String fieldName : fields) {
                     Terms terms = fields.terms(fieldName);
                     final TermsEnum termsEnum = terms.iterator();
@@ -248,12 +252,12 @@ public class MoreLikeThisQuery extends Query {
         setLikeText(likeText.toArray(Strings.EMPTY_ARRAY));
     }
 
-    public void setIgnoreText(Fields... ignoreFields) {
+    public void setUnlikeText(Fields... ignoreFields) {
-        this.ignoreFields = ignoreFields;
+        this.unlikeFields = ignoreFields;
     }
 
     public void setIgnoreText(List<String> ignoreText) {
-        this.ignoreText = ignoreText.toArray(Strings.EMPTY_ARRAY);
+        this.unlikeText = ignoreText.toArray(Strings.EMPTY_ARRAY);
     }
 
     public String[] getMoreLikeFields() {

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

@@ -130,7 +130,7 @@ public class MoreLikeThisQueryBuilder extends QueryBuilder implements BoostableQ
 
     private final String[] fields;
     private List<Item> docs = new ArrayList<>();
-    private List<Item> ignoreDocs = new ArrayList<>();
+    private List<Item> unlikeDocs = new ArrayList<>();
     private Boolean include = null;
     private String minimumShouldMatch = null;
     private int minTermFreq = -1;
@@ -189,7 +189,7 @@ public class MoreLikeThisQueryBuilder extends QueryBuilder implements BoostableQ
      * Sets the documents from which the terms should not be selected from.
      */
     public MoreLikeThisQueryBuilder ignoreLike(Item... docs) {
-        this.ignoreDocs = Arrays.asList(docs);
+        this.unlikeDocs = Arrays.asList(docs);
         return this;
     }
 
@@ -197,9 +197,9 @@ public class MoreLikeThisQueryBuilder extends QueryBuilder implements BoostableQ
      * Sets the text from which the terms should not be selected from.
      */
     public MoreLikeThisQueryBuilder ignoreLike(String... likeText) {
-        this.ignoreDocs = new ArrayList<>();
+        this.unlikeDocs = new ArrayList<>();
         for (String text : likeText) {
-            this.ignoreDocs.add(new Item(text));
+            this.unlikeDocs.add(new Item(text));
         }
         return this;
     }
@@ -378,8 +378,8 @@ public class MoreLikeThisQueryBuilder extends QueryBuilder implements BoostableQ
         } else {
             builder.field(likeFieldName, docs);
         }
-        if (!ignoreDocs.isEmpty()) {
+        if (!unlikeDocs.isEmpty()) {
-            builder.field(MoreLikeThisQueryParser.Fields.LIKE.getPreferredName(), ignoreDocs);
+            builder.field(MoreLikeThisQueryParser.Fields.UNLIKE.getPreferredName(), unlikeDocs);
         }
         if (minimumShouldMatch != null) {
             builder.field(MoreLikeThisQueryParser.Fields.MINIMUM_SHOULD_MATCH.getPreferredName(), minimumShouldMatch);

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

@@ -73,7 +73,7 @@ public class MoreLikeThisQueryParser implements QueryParser {
         public static final ParseField DOCUMENT_IDS = new ParseField("ids").withAllDeprecated("like");
         public static final ParseField DOCUMENTS = new ParseField("docs").withAllDeprecated("like");
         public static final ParseField LIKE = new ParseField("like");
-        public static final ParseField IGNORE_LIKE = new ParseField("ignore_like");
+        public static final ParseField UNLIKE = new ParseField("unlike");
         public static final ParseField INCLUDE = new ParseField("include");
     }
 
@@ -109,8 +109,8 @@ public class MoreLikeThisQueryParser implements QueryParser {
         List<String> likeTexts = new ArrayList<>();
         MultiTermVectorsRequest likeItems = new MultiTermVectorsRequest();
 
-        List<String> ignoreTexts = new ArrayList<>();
+        List<String> unlikeTexts = new ArrayList<>();
-        MultiTermVectorsRequest ignoreItems = new MultiTermVectorsRequest();
+        MultiTermVectorsRequest unlikeItems = new MultiTermVectorsRequest();
 
         while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
             if (token == XContentParser.Token.FIELD_NAME) {
@@ -120,8 +120,8 @@ public class MoreLikeThisQueryParser implements QueryParser {
                     likeTexts.add(parser.text());
                 } else if (Fields.LIKE.match(currentFieldName, parseContext.parseFlags())) {
                     parseLikeField(parser, likeTexts, likeItems);
-                } else if (Fields.IGNORE_LIKE.match(currentFieldName, parseContext.parseFlags())) {
+                } else if (Fields.UNLIKE.match(currentFieldName, parseContext.parseFlags())) {
-                    parseLikeField(parser, ignoreTexts, ignoreItems);
+                    parseLikeField(parser, unlikeTexts, unlikeItems);
                 } else if (Fields.MIN_TERM_FREQ.match(currentFieldName, parseContext.parseFlags())) {
                     mltQuery.setMinTermFrequency(parser.intValue());
                 } else if (Fields.MAX_QUERY_TERMS.match(currentFieldName, parseContext.parseFlags())) {
@@ -187,9 +187,9 @@ public class MoreLikeThisQueryParser implements QueryParser {
                     while ((token = parser.nextToken()) != XContentParser.Token.END_ARRAY) {
                         parseLikeField(parser, likeTexts, likeItems);
                     }
-                } else if (Fields.IGNORE_LIKE.match(currentFieldName, parseContext.parseFlags())) {
+                } else if (Fields.UNLIKE.match(currentFieldName, parseContext.parseFlags())) {
                     while ((token = parser.nextToken()) != XContentParser.Token.END_ARRAY) {
-                        parseLikeField(parser, ignoreTexts, ignoreItems);
+                        parseLikeField(parser, unlikeTexts, unlikeItems);
                     }
                 } else {
                     throw new QueryParsingException(parseContext, "[mlt] query does not support [" + currentFieldName + "]");
@@ -198,8 +198,8 @@ public class MoreLikeThisQueryParser implements QueryParser {
                 if (Fields.LIKE.match(currentFieldName, parseContext.parseFlags())) {
                     parseLikeField(parser, likeTexts, likeItems);
                 }
-                else if (Fields.IGNORE_LIKE.match(currentFieldName, parseContext.parseFlags())) {
+                else if (Fields.UNLIKE.match(currentFieldName, parseContext.parseFlags())) {
-                    parseLikeField(parser, ignoreTexts, ignoreItems);
+                    parseLikeField(parser, unlikeTexts, unlikeItems);
                 } else {
                     throw new QueryParsingException(parseContext, "[mlt] query does not support [" + currentFieldName + "]");
                 }
@@ -240,16 +240,15 @@ public class MoreLikeThisQueryParser implements QueryParser {
         if (!likeTexts.isEmpty()) {
             mltQuery.setLikeText(likeTexts);
         }
-        if (!ignoreTexts.isEmpty()) {
+        if (!unlikeTexts.isEmpty()) {
-            mltQuery.setIgnoreText(ignoreTexts);
+            mltQuery.setIgnoreText(unlikeTexts);
         }
 
         // handle items
         if (!likeItems.isEmpty()) {
             // set default index, type and fields if not specified
             MultiTermVectorsRequest items = likeItems;
-
+            for (TermVectorsRequest item : unlikeItems) {
-            for (TermVectorsRequest item : ignoreItems) {
                 items.add(item);
             }
 
@@ -283,10 +282,10 @@ public class MoreLikeThisQueryParser implements QueryParser {
             mltQuery.setLikeText(MoreLikeThisFetchService.getFields(responses, likeItems));
 
             // getting the Fields for ignored items
-            if (!ignoreItems.isEmpty()) {
+            if (!unlikeItems.isEmpty()) {
-                org.apache.lucene.index.Fields[] ignoreFields = MoreLikeThisFetchService.getFields(responses, ignoreItems);
+                org.apache.lucene.index.Fields[] ignoreFields = MoreLikeThisFetchService.getFields(responses, unlikeItems);
                 if (ignoreFields.length > 0) {
-                    mltQuery.setIgnoreText(ignoreFields);
+                    mltQuery.setUnlikeText(ignoreFields);
                 }
             }
 

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

@@ -162,15 +162,16 @@ follows a similar syntax to the `per_field_analyzer` parameter of the
 Additionally, to provide documents not necessarily present in the index,
 <<docs-termvectors-artificial-doc,artificial documents>> are also supported.
 
+`unlike`:: coming[2.0] 
+The `unlike` parameter is used in conjunction with `like` in order not to
+select terms found in a chosen set of documents. In other words, we could ask
+for documents `like: "Apple"`, but `unlike: "cake crumble tree"`. The syntax
+is the same as `like`.
+
 `fields`::
 A list of fields to fetch and analyze the text from. Defaults to the `_all`
 field for free text and to all possible fields for document inputs.
 
-`ignore_like`:: coming[2.0]
-The `ignore_like` parameter is used to skip the terms found in a chosen set of
-documents. In other words, we could ask for documents `like: "Apple"`, but
-`ignore_like: "cake crumble tree"`. The syntax is the same as `like`.
-
 `like_text`:: deprecated[2.0,Replaced by `like`]
 The text to find documents like it.
 

rest-api-spec/test/mlt/30_unlike.yaml

@@ -1,5 +1,5 @@
 ---
-"Basic mlt query with ignore like":
+"Basic mlt query with unlike":
   - do:
       indices.create:
         index: test_1
@@ -45,7 +45,7 @@
                     _index: test_1
                     _type: test
                     _id: 1
-                ignore_like:
+                unlike:
                     _index: test_1
                     _type: test
                     _id: 3