Improve error when sorting on incompatible types

docs/changelog/88399.yaml

@@ -0,0 +1,6 @@
+pr: 88399
+summary: Improve error when sorting on incompatible types
+area: Search
+type: enhancement
+issues:
+ - 73146

server/src/internalClusterTest/java/org/elasticsearch/search/sort/FieldSortIT.java

@@ -2122,4 +2122,43 @@ public void testLongSortOptimizationCorrectResults() {
         }
     }
 
+    public void testSortMixedFieldTypes() {
+        assertAcked(prepareCreate("index_long").setMapping("foo", "type=long").get());
+        assertAcked(prepareCreate("index_integer").setMapping("foo", "type=integer").get());
+        assertAcked(prepareCreate("index_double").setMapping("foo", "type=double").get());
+        assertAcked(prepareCreate("index_keyword").setMapping("foo", "type=keyword").get());
+
+        client().prepareIndex("index_long").setId("1").setSource("foo", "123").get();
+        client().prepareIndex("index_integer").setId("1").setSource("foo", "123").get();
+        client().prepareIndex("index_double").setId("1").setSource("foo", "123").get();
+        client().prepareIndex("index_keyword").setId("1").setSource("foo", "123").get();
+        refresh();
+
+        { // mixing long and integer types is ok, as we convert integer sort to long sort
+            SearchResponse searchResponse = client().prepareSearch("index_long", "index_integer")
+                .addSort(new FieldSortBuilder("foo"))
+                .setSize(10)
+                .get();
+            assertSearchResponse(searchResponse);
+        }
+
+        String errMsg = "Can't sort on field [foo]; the field has incompatible sort types";
+
+        { // mixing long and double types is not allowed
+            SearchPhaseExecutionException exc = expectThrows(
+                SearchPhaseExecutionException.class,
+                () -> client().prepareSearch("index_long", "index_double").addSort(new FieldSortBuilder("foo")).setSize(10).get()
+            );
+            assertThat(exc.getCause().toString(), containsString(errMsg));
+        }
+
+        { // mixing long and keyword types is not allowed
+            SearchPhaseExecutionException exc = expectThrows(
+                SearchPhaseExecutionException.class,
+                () -> client().prepareSearch("index_long", "index_keyword").addSort(new FieldSortBuilder("foo")).setSize(10).get()
+            );
+            assertThat(exc.getCause().toString(), containsString(errMsg));
+        }
+    }
+
 }

server/src/main/java/org/elasticsearch/action/search/SearchPhaseController.java

@@ -14,6 +14,8 @@
 import org.apache.lucene.search.ScoreDoc;
 import org.apache.lucene.search.Sort;
 import org.apache.lucene.search.SortField;
+import org.apache.lucene.search.SortedNumericSortField;
+import org.apache.lucene.search.SortedSetSortField;
 import org.apache.lucene.search.TermStatistics;
 import org.apache.lucene.search.TopDocs;
 import org.apache.lucene.search.TopFieldDocs;
@@ -197,6 +199,7 @@ static TopDocs mergeTopDocs(Collection<TopDocs> results, int topN, int from) {
             final TopFieldGroups[] shardTopDocs = results.toArray(new TopFieldGroups[numShards]);
             mergedTopDocs = TopFieldGroups.merge(sort, from, topN, shardTopDocs, false);
         } else if (topDocs instanceof TopFieldDocs firstTopDocs) {
+            assertSameSortTypes(results, firstTopDocs.fields);
             final Sort sort = new Sort(firstTopDocs.fields);
             final TopFieldDocs[] shardTopDocs = results.toArray(new TopFieldDocs[numShards]);
             mergedTopDocs = TopDocs.merge(sort, from, topN, shardTopDocs);
@@ -207,6 +210,56 @@ static TopDocs mergeTopDocs(Collection<TopDocs> results, int topN, int from) {
         return mergedTopDocs;
     }
 
+    private static void assertSameSortTypes(Collection<TopDocs> results, SortField[] firstSortFields) {
+        if (results.size() < 2) return;
+
+        SortField.Type[] firstTypes = new SortField.Type[firstSortFields.length];
+        boolean isFirstResult = true;
+        for (TopDocs topDocs : results) {
+            SortField[] curSortFields = ((TopFieldDocs) topDocs).fields;
+            if (isFirstResult) {
+                for (int i = 0; i < curSortFields.length; i++) {
+                    firstTypes[i] = getType(firstSortFields[i]);
+                    if (firstTypes[i] == SortField.Type.CUSTOM) {
+                        // for custom types that we can't resolve, we can't do the check
+                        return;
+                    }
+                }
+                isFirstResult = false;
+            } else {
+                for (int i = 0; i < curSortFields.length; i++) {
+                    SortField.Type curType = getType(curSortFields[i]);
+                    if (curType != firstTypes[i]) {
+                        if (curType == SortField.Type.CUSTOM) {
+                            // for custom types that we can't resolve, we can't do the check
+                            return;
+                        }
+                        throw new IllegalArgumentException(
+                            "Can't sort on field ["
+                                + curSortFields[i].getField()
+                                + "]; the field has incompatible sort types: ["
+                                + firstTypes[i]
+                                + "] and ["
+                                + curType
+                                + "] across shards!"
+                        );
+                    }
+                }
+            }
+        }
+    }
+
+    private static SortField.Type getType(SortField sortField) {
+        if (sortField instanceof SortedNumericSortField) {
+            return ((SortedNumericSortField) sortField).getNumericType();
+        }
+        if (sortField instanceof SortedSetSortField) {
+            return SortField.Type.STRING;
+        } else {
+            return sortField.getType();
+        }
+    }
+
     static void setShardIndex(TopDocs topDocs, int shardIndex) {
         assert topDocs.scoreDocs.length == 0 || topDocs.scoreDocs[0].shardIndex == -1 : "shardIndex is already set";
         for (ScoreDoc doc : topDocs.scoreDocs) {