[8.8] Fix NPE when indexing a document that just has been deleted in …

…a tsdb index (#96476)

Backporting #96461 to 8.8 branch.

Sometimes a segment only contains tombstone documents. In that case, loading min and max @timestamp field values can result into NPE. Because these documents don't have a @timestamp field.

This change fixes that by checking for the existence of the @timestamp field in the a segment's field infos.

docs/changelog/96461.yaml

@@ -0,0 +1,5 @@
+pr: 96461
+summary: Fix NPE when indexing a document that just has been deleted in a tsdb index
+area: TSDB
+type: bug
+issues: []

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/delete/70_tsdb.yml

@@ -0,0 +1,73 @@
+---
+"basic tsdb delete":
+  - skip:
+      version: " - 8.8.0"
+      reason: fixed in 8.8.1
+
+  - do:
+      indices.create:
+        index: weather_sensors
+        body:
+          settings:
+            index:
+              mode: time_series
+              routing_path: [sensor_id, location]
+              time_series:
+                start_time: 2000-01-01T00:00:00.000Z
+                end_time: 2099-12-31T23:59:59.999Z
+              number_of_replicas: 0
+              number_of_shards: 1
+          mappings:
+            properties:
+              "@timestamp":
+                type: date
+              humidity:
+                type: half_float
+                time_series_metric: gauge
+              location:
+                type: keyword
+                time_series_dimension: true
+              sensor_id:
+                type: keyword
+                time_series_dimension: true
+              temperature:
+                type: half_float
+                time_series_metric: gauge
+
+  - do:
+      index:
+        index: weather_sensors
+        body:
+          "@timestamp": 2023-05-31T08:41:15.000Z
+          sensor_id: SYKENET-000001
+          location: swamp
+          temperature: 32.4
+          humidity: 88.9
+  - match:   { _id: crxuhC8WO3aVdhvtAAABiHD35_g }
+  - match:   { result: created }
+  - match:   { _version: 1 }
+
+  - do:
+      delete:
+        index: weather_sensors
+        id: crxuhC8WO3aVdhvtAAABiHD35_g
+  - match:   { _id: crxuhC8WO3aVdhvtAAABiHD35_g }
+  - match:   { result: deleted }
+  - match:   { _version: 2 }
+
+  - do:
+      indices.flush:
+        index: weather_sensors
+
+  - do:
+      index:
+        index: weather_sensors
+        body:
+          "@timestamp": 2023-05-31T08:41:15.000Z
+          sensor_id: SYKENET-000001
+          location: swamp
+          temperature: 32.4
+          humidity: 88.9
+  - match:   { _id: crxuhC8WO3aVdhvtAAABiHD35_g }
+  - match:   { result: created }
+  - match:   { _version: 3 }

server/src/main/java/org/elasticsearch/common/lucene/uid/PerThreadIDVersionAndSeqNoLookup.java

@@ -94,7 +94,9 @@ final class PerThreadIDVersionAndSeqNoLookup {
         this.readerKey = readerKey;
 
         this.loadedTimestampRange = loadTimestampRange;
-        if (loadTimestampRange) {
+        // Also check for the existence of the timestamp field, because sometimes a segment can only contain tombstone documents,
+        // which don't have any mapped fields (also not the timestamp field) and just some meta fields like _id, _seq_no etc.
+        if (loadTimestampRange && reader.getFieldInfos().fieldInfo(DataStream.TimestampField.FIXED_TIMESTAMP_FIELD) != null) {
             PointValues tsPointValues = reader.getPointValues(DataStream.TimestampField.FIXED_TIMESTAMP_FIELD);
             assert tsPointValues != null : "no timestamp field for reader:" + reader + " and parent:" + reader.getContext().parent.reader();
             minTimestamp = LongPoint.decodeDimension(tsPointValues.getMinPackedValue(), 0);

server/src/test/java/org/elasticsearch/common/lucene/uid/VersionLookupTests.java

@@ -25,6 +25,7 @@
 import org.elasticsearch.common.lucene.Lucene;
 import org.elasticsearch.common.lucene.uid.VersionsAndSeqNoResolver.DocIdAndVersion;
 import org.elasticsearch.index.mapper.IdFieldMapper;
+import org.elasticsearch.index.mapper.ParsedDocument;
 import org.elasticsearch.index.mapper.SeqNoFieldMapper;
 import org.elasticsearch.index.mapper.VersionFieldMapper;
 import org.elasticsearch.test.ESTestCase;
@@ -152,4 +153,19 @@ public void testLoadTimestampRange() throws Exception {
         writer.close();
         dir.close();
     }
+
+    public void testLoadTimestampRangeWithDeleteTombstone() throws Exception {
+        Directory dir = newDirectory();
+        IndexWriter writer = new IndexWriter(dir, new IndexWriterConfig(Lucene.STANDARD_ANALYZER).setMergePolicy(NoMergePolicy.INSTANCE));
+        writer.addDocument(ParsedDocument.deleteTombstone("_id").docs().get(0));
+        DirectoryReader reader = DirectoryReader.open(writer);
+        LeafReaderContext segment = reader.leaves().get(0);
+        PerThreadIDVersionAndSeqNoLookup lookup = new PerThreadIDVersionAndSeqNoLookup(segment.reader(), IdFieldMapper.NAME, true);
+        assertTrue(lookup.loadedTimestampRange);
+        assertEquals(lookup.minTimestamp, 0L);
+        assertEquals(lookup.maxTimestamp, Long.MAX_VALUE);
+        reader.close();
+        writer.close();
+        dir.close();
+    }
 }