PMM-13602 Improve performance for callstats

Author: BupycHuk

exporter/collstats_collector.go

@@ -37,12 +37,12 @@ type collstatsCollector struct {
 }
 
 // newCollectionStatsCollector creates a collector for statistics about collections.
-func newCollectionStatsCollector(ctx context.Context, client *mongo.Client, logger *logrus.Logger, compatible, discovery bool, topology labelsGetter, collections []string) *collstatsCollector {
+func newCollectionStatsCollector(ctx context.Context, client *mongo.Client, logger *logrus.Logger, discovery bool, topology labelsGetter, collections []string) *collstatsCollector {
 	return &collstatsCollector{
 		ctx:  ctx,
 		base: newBaseCollector(client, logger.WithFields(logrus.Fields{"collector": "collstats"})),
 
-		compatibleMode:  compatible,
+		compatibleMode:  false, //there are no compatible metrics for this collector.
 		discoveringMode: discovery,
 		topologyInfo:    topology,
 
@@ -107,8 +107,18 @@ func (d *collstatsCollector) collect(ch chan<- prometheus.Metric) {
 				},
 			},
 		}
+		project := bson.D{
+			{
+				Key: "$project", Value: bson.M{
+					"storageStats.wiredTiger":   0,
+					"storageStats.indexDetails": 0,
+				},
+			},
+		}
+
+		pipeline := mongo.Pipeline{aggregation, project}
 
-		cursor, err := client.Database(database).Collection(collection).Aggregate(d.ctx, mongo.Pipeline{aggregation})
+		cursor, err := client.Database(database).Collection(collection).Aggregate(d.ctx, pipeline)
 		if err != nil {
 			logger.Errorf("cannot get $collstats cursor for collection %s.%s: %s", database, collection, err)
 

exporter/collstats_collector_test.go

@@ -54,7 +54,7 @@ func TestCollStatsCollector(t *testing.T) {
 
 	collection := []string{"testdb.testcol_00", "testdb.testcol_01", "testdb.testcol_02"}
 	logger := logrus.New()
-	c := newCollectionStatsCollector(ctx, client, logger, false, false, ti, collection)
+	c := newCollectionStatsCollector(ctx, client, logger, false, ti, collection)
 
 	// The last \n at the end of this string is important
 	expected := strings.NewReader(`