RavenDB-22953 Fixing sorting edge case in Corax where all matches hav…

…e been found already so there is no need to fallback to normal sorting (which expected to get non empty batch of results)

src/Corax/Querying/Matches/SortingMatches/SortingMatch.cs

@@ -437,10 +437,14 @@ private static void SortUsingIndex<TEntryComparer, TDirection>(ref SortingMatch<
                 // direct SortResult, but first we need to remove all the items that we already matched
                 int notMatchedYet = FilterAlreadyFoundMatches(allMatches);
 
-                // if we scanned through the index more than twice the amount of records of the query, but still
-                // didn't find enough to fill the page size, we'll fall back to normal sorting, instead of using the
-                // index method. That would prevent degenerate cases.
-                SortResults<TEntryComparer>(ref match, allMatches[..notMatchedYet]);
+                if (notMatchedYet > 0)
+                {
+                    // if we scanned through the index more than twice the amount of records of the query, but still
+                    // didn't find enough to fill the page size, we'll fall back to normal sorting, instead of using the
+                    // index method. That would prevent degenerate cases.
+                    SortResults<TEntryComparer>(ref match, allMatches[..notMatchedYet]);
+                }
+
                 return;
             }
 

test/SlowTests/Corax/RavenDB_22953.cs

@@ -0,0 +1,121 @@
+using System;
+using System.Globalization;
+using System.Linq;
+using FastTests;
+using Raven.Client.Documents.Indexes;
+using Tests.Infrastructure;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace SlowTests.Corax;
+
+public class RavenDB_22953 : RavenTestBase
+{
+    public RavenDB_22953(ITestOutputHelper output) : base(output)
+    {
+    }
+
+    [RavenTheory(RavenTestCategory.Corax)]
+    [RavenData(SearchEngineMode = RavenSearchEngineMode.Corax)]
+    public void StreamingQueryMustNotThrowIndexOutOfRangeException(Options options)
+    {
+        using (var store = GetDocumentStore(options))
+        {
+            var timestamps = new[]
+            {
+                new DateTimeOffset(new DateTime(2024, 9, 2), TimeSpan.Zero),
+                new DateTimeOffset(new DateTime(2024, 9, 3), TimeSpan.Zero),
+                new DateTimeOffset(new DateTime(2024, 9, 5), TimeSpan.Zero),
+                new DateTimeOffset(new DateTime(2024, 9, 12), TimeSpan.Zero),
+                new DateTimeOffset(new DateTime(2024, 9, 13), TimeSpan.Zero),
+                new DateTimeOffset(new DateTime(2024, 9, 15), TimeSpan.Zero),
+                new DateTimeOffset(new DateTime(2024, 9, 17), TimeSpan.Zero),
+                new DateTimeOffset(new DateTime(2024, 9, 20), TimeSpan.Zero),
+                new DateTimeOffset(new DateTime(2024, 9, 21), TimeSpan.Zero),
+                new DateTimeOffset(new DateTime(2024, 9, 22), TimeSpan.Zero),
+                new DateTimeOffset(new DateTime(2024, 9, 22), TimeSpan.Zero),
+                new DateTimeOffset(new DateTime(2024, 9, 27), TimeSpan.Zero),
+            };
+
+            using (var bulk = store.BulkInsert())
+            {
+                for (int i = 0; i < 10000; i++)
+                {
+                    bulk.Store(new Entry
+                    {
+                        Timestamp = timestamps[i % timestamps.Length],
+                        Schema = "foo",
+                        Name = "bar"
+                    });
+                }
+            }
+
+            using (var bulk = store.BulkInsert())
+            {
+                for (int i = 0; i < 11000; i++)
+                {
+                    bulk.Store(new Entry
+                    {
+                        Timestamp = timestamps[i % timestamps.Length],
+                        Schema = "zzz",
+                        Name = "bar"
+                    });
+                }
+            }
+
+            new Entries_ByTimestampAndQualifiedName().Execute(store);
+
+            Indexes.WaitForIndexing(store);
+
+            using (var session = store.OpenSession())
+            {
+                var count = 0;
+
+                var q = session.Advanced.DocumentQuery<Entries_ByTimestampAndQualifiedName.IndexEntry, Entries_ByTimestampAndQualifiedName>()
+                    .WhereGreaterThanOrEqual(x => x.Timestamp, new DateTimeOffset(new DateTime(2024, 9, 2), TimeSpan.Zero))
+                    .WhereLessThanOrEqual(x => x.Timestamp, new DateTimeOffset(new DateTime(2024, 9, 27), TimeSpan.Zero))
+                    .WhereIn(x => x.QualifiedName, new[] { "foo:bar" })
+                    .OrderBy(x => x.Timestamp);
+
+                var s = session.Advanced.Stream(q);
+
+                while (s.MoveNext())
+                {
+                    count++;
+                }
+
+                Assert.Equal(10000, count);
+            }
+        }
+    }
+
+    private class Entry
+    {
+        public DateTimeOffset? Timestamp { get; set; }
+
+        public string Name { get; set; }
+
+        public string Schema { get; set; }
+    }
+
+    private class Entries_ByTimestampAndQualifiedName : AbstractIndexCreationTask<Entry>
+    {
+        public class IndexEntry
+        {
+            public DateTimeOffset Timestamp { get; set; }
+
+            public string QualifiedName { get; set; }
+        }
+
+        public Entries_ByTimestampAndQualifiedName()
+        {
+            Map = entries => from entry in entries
+                select new IndexEntry
+                {
+                    Timestamp = entry.Timestamp ??
+                                default(DateTimeOffset),
+                    QualifiedName = string.Format("{0}:{1}", entry.Schema, entry.Name),
+                };
+        }
+    }
+}