MQE: fix panic in rate or increase over native histograms with ch…

…anging schema (#9518) * MQE: fix panic in `rate` or `increase` over native histograms with changing schema * Add changelog entry * Add test for `increase` too
grafana · Oct 4, 2024 · caa2fb9 · caa2fb9
1 parent 665bb0f
commit caa2fb9
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Showing 3 changed files with 18 additions and 6 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -14,7 +14,7 @@
   * `cortex_alertmanager_alerts`
   * `cortex_alertmanager_silences`
 * [CHANGE] Cache: Deprecate experimental support for Redis as a cache backend. #9453
-* [FEATURE] Querier: add experimental streaming PromQL engine, enabled with `-querier.query-engine=mimir`. #9367 #9368 #9398 #9399 #9403 #9417 #9418 #9419 #9420 #9482 #9504 #9505 #9507
+* [FEATURE] Querier: add experimental streaming PromQL engine, enabled with `-querier.query-engine=mimir`. #9367 #9368 #9398 #9399 #9403 #9417 #9418 #9419 #9420 #9482 #9504 #9505 #9507 #9518
 * [FEATURE] Query-frontend: added experimental configuration options `query-frontend.cache-errors` and `query-frontend.results-cache-ttl-for-errors` to allow non-transient responses to be cached. When set to `true` error responses from hitting limits or bad data are cached for a short TTL. #9028
 * [FEATURE] gRPC: Support S2 compression. #9322
   * `-alertmanager.alertmanager-client.grpc-compression=s2`

diff --git a/pkg/streamingpromql/functions/rate_increase.go b/pkg/streamingpromql/functions/rate_increase.go
@@ -84,17 +84,17 @@ func histogramRate(isRate bool, step types.RangeVectorStepData, hHead []promql.H
 		emitAnnotation(annotations.NewNativeHistogramNotCounterWarning)
 	}
 
-	currentSchema := firstPoint.H.Schema
-	if lastPoint.H.Schema < currentSchema {
-		currentSchema = lastPoint.H.Schema
+	initialSchema := firstPoint.H.Schema
+	if lastPoint.H.Schema < initialSchema {
+		initialSchema = lastPoint.H.Schema
 	}
 
 	usingCustomBuckets := firstPoint.H.UsesCustomBuckets()
 	if lastPoint.H.UsesCustomBuckets() != usingCustomBuckets {
 		return nil, histogram.ErrHistogramsIncompatibleSchema
 	}
 
-	delta := lastPoint.H.CopyToSchema(currentSchema)
+	delta := lastPoint.H.CopyToSchema(initialSchema)
 	_, err := delta.Sub(firstPoint.H)
 	if err != nil {
 		return nil, err
@@ -114,7 +114,7 @@ func histogramRate(isRate bool, step types.RangeVectorStepData, hHead []promql.H
 				return histogram.ErrHistogramsIncompatibleSchema
 			}
 
-			if p.H.Schema < currentSchema {
+			if p.H.Schema < delta.Schema {
 				delta = delta.CopyToSchema(p.H.Schema)
 			}
 

diff --git a/pkg/streamingpromql/testdata/ours/native_histograms.test b/pkg/streamingpromql/testdata/ours/native_histograms.test
@@ -201,3 +201,15 @@ load 6m
 # T=18: compatible
 eval_warn range from 0 to 18m step 6m sum(metric)
   {} _ {{schema:-53 sum:2 count:2 custom_values:[5 10] buckets:[2 4]}} _ {{schema:-53 sum:3.8 count:6 custom_values:[3] buckets:[6]}}
+
+clear
+
+# Test rate() and increase() over native histograms with changing schemas.
+load 1m
+  metric {{schema:4 sum:2 count:2 buckets:[2]}} {{schema:2 sum:6 count:12 buckets:[12]}} {{schema:3 sum:12 count:24 buckets:[24]}} {{schema:4 sum:164 count:326 buckets:[326]}}
+
+eval instant at 3m rate(metric[3m])
+  {} {{schema:2 sum:1 count:2 buckets:[2] counter_reset_hint:gauge}}
+
+eval instant at 3m increase(metric[3m])
+  {} {{schema:2 sum:180 count:360 buckets:[360] counter_reset_hint:gauge}}