Copy metrics and default_metric properties when downsampling aggregate_metric_double (#121727)

Fixes #119696 and #96076

docs/changelog/121727.yaml

@@ -0,0 +1,7 @@
+pr: 121727
+summary: Copy metrics and `default_metric` properties when downsampling `aggregate_metric_double`
+area: Downsampling
+type: bug
+issues:
+ - 119696
+ - 96076

modules/data-streams/src/main/java/org/elasticsearch/datastreams/DataStreamFeatures.java

@@ -21,6 +21,10 @@ public class DataStreamFeatures implements FeatureSpecification {
 
     public static final NodeFeature DATA_STREAM_FAILURE_STORE_TSDB_FIX = new NodeFeature("data_stream.failure_store.tsdb_fix");
 
+    public static final NodeFeature DOWNSAMPLE_AGGREGATE_DEFAULT_METRIC_FIX = new NodeFeature(
+        "data_stream.downsample.default_aggregate_metric_fix"
+    );
+
     @Override
     public Set<NodeFeature> getFeatures() {
         return Set.of();
@@ -28,6 +32,6 @@ public class DataStreamFeatures implements FeatureSpecification {
 
     @Override
     public Set<NodeFeature> getTestFeatures() {
-        return Set.of(DATA_STREAM_FAILURE_STORE_TSDB_FIX);
+        return Set.of(DATA_STREAM_FAILURE_STORE_TSDB_FIX, DOWNSAMPLE_AGGREGATE_DEFAULT_METRIC_FIX);
     }
 }

x-pack/plugin/downsample/qa/rest/src/yamlRestTest/resources/rest-api-spec/test/downsample/80_downsample_aggregate.yml

@@ -0,0 +1,79 @@
+"downsample aggregate field":
+  - requires:
+      cluster_features: ["data_stream.downsample.default_aggregate_metric_fix"]
+      reason: "#119696 fixed"
+
+  - do:
+      indices.create:
+        index: test
+        body:
+          settings:
+            number_of_shards: 1
+            index:
+              mode: time_series
+              routing_path: [sensor_id]
+              time_series:
+                start_time: 2021-04-28T00:00:00Z
+                end_time: 2021-04-29T00:00:00Z
+          mappings:
+            properties:
+              "@timestamp":
+                type: date
+              sensor_id:
+                type: keyword
+                time_series_dimension: true
+              temperature:
+                type: aggregate_metric_double
+                metrics: [min, sum, value_count]
+                default_metric: sum
+                time_series_metric: gauge
+  - do:
+      bulk:
+        refresh: true
+        index: test
+        body:
+          - '{"index": {}}'
+          - '{"@timestamp": "2021-04-28T18:00:00Z", "sensor_id": "1", "temperature": {"min": 24.7, "sum": 50.2, "value_count": 2}}'
+          - '{"index": {}}'
+          - '{"@timestamp": "2021-04-28T18:30:00Z", "sensor_id": "1", "temperature": {"min": 24.2, "sum": 73.8, "value_count": 3}}'
+          - '{"index": {}}'
+          - '{"@timestamp": "2021-04-28T19:00:00Z", "sensor_id": "1", "temperature": {"min": 25.1, "sum": 51.0, "value_count": 2}}'
+          - '{"index": {}}'
+          - '{"@timestamp": "2021-04-28T19:30:00Z", "sensor_id": "1", "temperature": {"min": 24.8, "sum": 24.8, "value_count": 1}}'
+          - '{"index": {}}'
+          - '{"@timestamp": "2021-04-28T20:00:00Z", "sensor_id": "1", "temperature": {"min": 24.6, "sum": 49.1, "value_count": 2}}'
+
+  - do:
+      indices.put_settings:
+        index: test
+        body:
+          index.blocks.write: true
+
+  - do:
+      indices.downsample:
+        index: test
+        target_index: test-downsample
+        body:  >
+          {
+            "fixed_interval": "1h"
+          }
+  - is_true: acknowledged
+
+  - do:
+      search:
+        index: test-downsample
+        body:
+          size: 0
+
+  - match:
+      hits.total.value: 3
+
+  - do:
+      indices.get_mapping:
+        index: test-downsample
+  - match:
+      test-downsample.mappings.properties.temperature:
+        type: aggregate_metric_double
+        metrics: [min, sum, value_count]
+        default_metric: sum
+        time_series_metric: gauge

x-pack/plugin/downsample/src/main/java/org/elasticsearch/xpack/downsample/TransportDownsampleAction.java

@@ -91,6 +91,7 @@ import java.time.format.DateTimeFormatter;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -739,6 +740,39 @@ public class TransportDownsampleAction extends AcknowledgedTransportMasterNodeAc
             .endObject();
     }
 
+    // public for testing
+    public record AggregateMetricDoubleFieldSupportedMetrics(String defaultMetric, List<String> supportedMetrics) {}
+
+    // public for testing
+    public static AggregateMetricDoubleFieldSupportedMetrics getSupportedMetrics(
+        final TimeSeriesParams.MetricType metricType,
+        final Map<String, ?> fieldProperties
+    ) {
+        boolean sourceIsAggregate = fieldProperties.get("type").equals(AggregateMetricDoubleFieldMapper.CONTENT_TYPE);
+        List<String> supportedAggs = List.of(metricType.supportedAggs());
+
+        if (sourceIsAggregate) {
+            @SuppressWarnings("unchecked")
+            List<String> currentAggs = (List<String>) fieldProperties.get(AggregateMetricDoubleFieldMapper.Names.METRICS);
+            supportedAggs = supportedAggs.stream().filter(currentAggs::contains).toList();
+        }
+
+        assert supportedAggs.size() > 0;
+
+        String defaultMetric = "max";
+        if (supportedAggs.contains(defaultMetric) == false) {
+            defaultMetric = supportedAggs.get(0);
+        }
+        if (sourceIsAggregate) {
+            defaultMetric = Objects.requireNonNullElse(
+                (String) fieldProperties.get(AggregateMetricDoubleFieldMapper.Names.DEFAULT_METRIC),
+                defaultMetric
+            );
+        }
+
+        return new AggregateMetricDoubleFieldSupportedMetrics(defaultMetric, supportedAggs);
+    }
+
     private static void addMetricFieldMapping(final XContentBuilder builder, final String field, final Map<String, ?> fieldProperties)
         throws IOException {
         final TimeSeriesParams.MetricType metricType = TimeSeriesParams.MetricType.fromString(
@@ -752,12 +786,11 @@ public class TransportDownsampleAction extends AcknowledgedTransportMasterNodeAc
                 builder.field(fieldProperty, fieldProperties.get(fieldProperty));
             }
         } else {
-            final String[] supportedAggsArray = metricType.supportedAggs();
+            var supported = getSupportedMetrics(metricType, fieldProperties);
-            // We choose max as the default metric
+
-            final String defaultMetric = List.of(supportedAggsArray).contains("max") ? "max" : supportedAggsArray[0];
             builder.field("type", AggregateMetricDoubleFieldMapper.CONTENT_TYPE)
-                .array(AggregateMetricDoubleFieldMapper.Names.METRICS, supportedAggsArray)
+                .stringListField(AggregateMetricDoubleFieldMapper.Names.METRICS, supported.supportedMetrics)
-                .field(AggregateMetricDoubleFieldMapper.Names.DEFAULT_METRIC, defaultMetric)
+                .field(AggregateMetricDoubleFieldMapper.Names.DEFAULT_METRIC, supported.defaultMetric)
                 .field(TIME_SERIES_METRIC_PARAM, metricType);
         }
         builder.endObject();

x-pack/plugin/downsample/src/test/java/org/elasticsearch/xpack/downsample/TransportDownsampleActionTests.java

@@ -13,12 +13,16 @@ import org.elasticsearch.common.settings.IndexScopedSettings;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.IndexVersion;
+import org.elasticsearch.index.mapper.TimeSeriesParams;
 import org.elasticsearch.test.ESTestCase;
 import org.elasticsearch.xpack.core.ilm.LifecycleSettings;
 
 import java.util.List;
+import java.util.Map;
 import java.util.UUID;
 
+import static org.hamcrest.Matchers.is;
+
 public class TransportDownsampleActionTests extends ESTestCase {
     public void testCopyIndexMetadata() {
         // GIVEN
@@ -107,4 +111,25 @@ public class TransportDownsampleActionTests extends ESTestCase {
             settings.get(IndexMetadata.SETTING_CREATION_DATE)
         );
     }
+
+    public void testGetSupportedMetrics() {
+        TimeSeriesParams.MetricType metricType = TimeSeriesParams.MetricType.GAUGE;
+        Map<String, Object> fieldProperties = Map.of(
+            "type",
+            "aggregate_metric_double",
+            "metrics",
+            List.of("max", "sum"),
+            "default_metric",
+            "sum"
+        );
+
+        var supported = TransportDownsampleAction.getSupportedMetrics(metricType, fieldProperties);
+        assertThat(supported.defaultMetric(), is("sum"));
+        assertThat(supported.supportedMetrics(), is(List.of("max", "sum")));
+
+        fieldProperties = Map.of("type", "integer");
+        supported = TransportDownsampleAction.getSupportedMetrics(metricType, fieldProperties);
+        assertThat(supported.defaultMetric(), is("max"));
+        assertThat(supported.supportedMetrics(), is(List.of(metricType.supportedAggs())));
+    }
 }