Search: deprecate the limit filter.

This is really a Collector instead of a filter. This commit deprecates the
`limit` filter, makes it a no-op and recommends to use the `terminate_after`
parameter instead that we introduced in the meantime.

docs/reference/migration/migrate_2_0.asciidoc

@@ -380,3 +380,8 @@ http.cors.allow-origin: /https?:\/\/localhost(:[0-9]+)?/
 The cluster state api doesn't return the `routing_nodes` section anymore when
 `routing_table` is requested. The newly introduced `routing_nodes` flag can
 be used separately to control whether `routing_nodes` should be returned.
+
+=== Query DSL
+
+The `limit` filter is deprecated and becomes a no-op. You can achieve similar
+behaviour using the <<search-request-body,terminate_after>> parameter.

docs/reference/query-dsl/filters/limit-filter.asciidoc

@@ -1,6 +1,8 @@
 [[query-dsl-limit-filter]]
 === Limit Filter
 
+deprecated[2.0.0, Use <<search-request-body,terminate_after>> instead]
+
 A limit filter limits the number of documents (per shard) to execute on.
 For example:
 

src/main/java/org/elasticsearch/index/query/FilterBuilders.java

@@ -19,6 +19,7 @@
 
 package org.elasticsearch.index.query;
 
+import org.elasticsearch.action.search.SearchRequestBuilder;
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.geo.GeoPoint;
@@ -39,7 +40,9 @@ public static MatchAllFilterBuilder matchAllFilter() {
 
     /**
      * A filter that limits the results to the provided limit value (per shard!).
+     * @deprecated Use {@link SearchRequestBuilder#setTerminateAfter(int)} instead.
      */
+    @Deprecated
     public static LimitFilterBuilder limitFilter(int limit) {
         return new LimitFilterBuilder(limit);
     }

src/main/java/org/elasticsearch/index/query/LimitFilterBuilder.java

@@ -19,10 +19,15 @@
 
 package org.elasticsearch.index.query;
 
+import org.elasticsearch.action.search.SearchRequestBuilder;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
 
+/**
+ * @deprecated Use {@link SearchRequestBuilder#setTerminateAfter(int)} instead.
+ */
+@Deprecated
 public class LimitFilterBuilder extends BaseFilterBuilder {
 
     private final int limit;

src/main/java/org/elasticsearch/index/query/LimitFilterParser.java

@@ -21,7 +21,7 @@
 
 import org.apache.lucene.search.Filter;
 import org.elasticsearch.common.inject.Inject;
-import org.elasticsearch.common.lucene.search.LimitFilter;
+import org.elasticsearch.common.lucene.search.Queries;
 import org.elasticsearch.common.xcontent.XContentParser;
 
 import java.io.IOException;
@@ -62,6 +62,7 @@ public Filter parse(QueryParseContext parseContext) throws IOException, QueryPar
             throw new QueryParsingException(parseContext.index(), "No value specified for limit filter");
         }
 
-        return new LimitFilter(limit);
+        // this filter is deprecated and parses to a filter that matches everything
+        return Queries.MATCH_ALL_FILTER;
     }
 }

src/test/java/org/elasticsearch/count/query/CountQueryTests.java

@@ -303,7 +303,7 @@ public void testLimitFilter() throws Exception {
                 client().prepareIndex("test", "type1", "4").setSource("field3", "value3_4"));
 
         CountResponse countResponse = client().prepareCount().setQuery(filteredQuery(matchAllQuery(), limitFilter(2))).get();
-        assertHitCount(countResponse, 2l);
+        assertHitCount(countResponse, 4l); // limit is a no-op
     }
 
     @Test

src/test/java/org/elasticsearch/index/query/SimpleIndexQueryParserTests.java

@@ -1281,20 +1281,6 @@ public void testFilteredQuery4() throws IOException {
         assertThat(getTerm(filteredQuery.getFilter()), equalTo(new Term("name.last", "banon")));
     }
 
-    @Test
-    public void testLimitFilter() throws Exception {
-        IndexQueryParserService queryParser = queryParser();
-        String query = copyToStringFromClasspath("/org/elasticsearch/index/query/limit-filter.json");
-        Query parsedQuery = queryParser.parse(query).query();
-        assertThat(parsedQuery, instanceOf(FilteredQuery.class));
-        FilteredQuery filteredQuery = (FilteredQuery) parsedQuery;
-        assertThat(filteredQuery.getFilter(), instanceOf(LimitFilter.class));
-        assertThat(((LimitFilter) filteredQuery.getFilter()).getLimit(), equalTo(2));
-
-        assertThat(filteredQuery.getQuery(), instanceOf(TermQuery.class));
-        assertThat(((TermQuery) filteredQuery.getQuery()).getTerm(), equalTo(new Term("name.first", "shay")));
-    }
-
     @Test
     public void testTermFilterQuery() throws Exception {
         IndexQueryParserService queryParser = queryParser();

src/test/java/org/elasticsearch/search/query/SearchQueryTests.java

@@ -677,7 +677,7 @@ public void testLimitFilter() throws Exception {
                 client().prepareIndex("test", "type1", "3").setSource("field2", "value2_3"),
                 client().prepareIndex("test", "type1", "4").setSource("field3", "value3_4"));
 
-        assertHitCount(client().prepareSearch().setQuery(filteredQuery(matchAllQuery(), limitFilter(2))).get(), 2l);
+        assertHitCount(client().prepareSearch().setQuery(filteredQuery(matchAllQuery(), limitFilter(2))).get(), 4l); // no-op
     }
 
     @Test