Avoid search_after short cutting in case of missing is specified

Signed-off-by: gashutos <gashutos@amazon.com>
opensearch-project · Jul 1, 2023 · 0a3a30e · 0a3a30e
1 parent 665d237
commit 0a3a30e
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Showing 2 changed files with 20 additions and 1 deletion.
diff --git a/server/src/main/java/org/opensearch/search/SearchService.java b/server/src/main/java/org/opensearch/search/SearchService.java
@@ -1550,7 +1550,9 @@ private CanMatchResponse canMatch(ShardSearchRequest request, boolean checkRefre
     }
 
     public static boolean canMatchSearchAfter(FieldDoc searchAfter, MinAndMax<?> minMax, FieldSortBuilder primarySortField) {
-        if (searchAfter != null && minMax != null && primarySortField != null) {
+        // Check for sort.missing == null, since in case of missing values sort queries, if segment/shard's min/max
+        // is out of search_after range, it still should be printed and hence we should not skip segment/shard.
+        if (searchAfter != null && minMax != null && primarySortField != null && primarySortField.missing() == null) {
             final Object searchAfterPrimary = searchAfter.fields[0];
             if (primarySortField.order() == SortOrder.DESC) {
                 if (minMax.compareMin(searchAfterPrimary) > 0) {

diff --git a/server/src/test/java/org/opensearch/search/SearchServiceTests.java b/server/src/test/java/org/opensearch/search/SearchServiceTests.java
@@ -1748,4 +1748,21 @@ public void testCanMatchSearchAfterDescEqualMin() throws IOException {
         primarySort.order(SortOrder.DESC);
         assertEquals(SearchService.canMatchSearchAfter(searchAfter, minMax, primarySort), true);
     }
+
+    /**
+     * Test canMatchSearchAfter with missing value, even if min/max is out of range
+     * Min = 0L, Max = 9L, search_after = -1L
+     * Expected result is canMatch = true
+     */
+    public void testCanMatchSearchAfterWithMissing() throws IOException {
+        FieldDoc searchAfter = new FieldDoc(0, 0, new Long[] { -1L });
+        MinAndMax<?> minMax = new MinAndMax<Long>(0L, 9L);
+        FieldSortBuilder primarySort = new FieldSortBuilder("test");
+        primarySort.order(SortOrder.DESC);
+        // Should be false without missing values
+        assertEquals(SearchService.canMatchSearchAfter(searchAfter, minMax, primarySort), false);
+        primarySort.missing("_last");
+        // Should be true with missing values
+        assertEquals(SearchService.canMatchSearchAfter(searchAfter, minMax, primarySort), true);
+    }
 }