planCache enhancement for top_query collection

Author: sv-splunk

receiver/sqlserverreceiver/factory.go

@@ -132,14 +132,16 @@ func setupSQLServerScrapers(params receiver.Settings, cfg *Config) []*sqlServerS
 
 		// lru only returns error when the size is less than 0
 		cache := newCache(1)
+		planCache, _ := lru.New[string, string](1)
 
 		sqlServerScraper := newSQLServerScraper(id, query,
 			sqlquery.TelemetryConfig{},
 			dbProviderFunc,
 			sqlquery.NewDbClient,
 			params,
 			cfg,
-			cache)
+			cache,
+			planCache)
 
 		scrapers = append(scrapers, sqlServerScraper)
 	}
@@ -172,6 +174,7 @@ func setupSQLServerLogsScrapers(params receiver.Settings, cfg *Config) []*sqlSer
 		id := component.NewIDWithName(metadata.Type, fmt.Sprintf("logs-query-%d: %s", i, query))
 
 		cache := newCache(1)
+		planCache, _ := lru.New[string, string](int(cfg.MaxQuerySampleCount))
 
 		if query == getSQLServerQueryTextAndPlanQuery() {
 			// we have 8 metrics in this query and multiple 2 to allow to cache more queries.
@@ -188,7 +191,8 @@ func setupSQLServerLogsScrapers(params receiver.Settings, cfg *Config) []*sqlSer
 			sqlquery.NewDbClient,
 			params,
 			cfg,
-			cache)
+			cache,
+			planCache)
 
 		scrapers = append(scrapers, sqlServerScraper)
 	}

receiver/sqlserverreceiver/scraper.go

@@ -62,6 +62,7 @@ type sqlServerScraperHelper struct {
 	mb                     *metadata.MetricsBuilder
 	lb                     *metadata.LogsBuilder
 	cache                  *lru.Cache[string, int64]
+	planCache              *lru.Cache[string, string]
 	lastExecutionTimestamp time.Time
 	obfuscator             *obfuscator
 	serviceInstanceID      string
@@ -80,6 +81,7 @@ func newSQLServerScraper(id component.ID,
 	params receiver.Settings,
 	cfg *Config,
 	cache *lru.Cache[string, int64],
+	planCache *lru.Cache[string, string],
 ) *sqlServerScraperHelper {
 	// Compute service instance ID
 	serviceInstanceID, err := computeServiceInstanceID(cfg)
@@ -99,6 +101,7 @@ func newSQLServerScraper(id component.ID,
 		mb:                     metadata.NewMetricsBuilder(cfg.MetricsBuilderConfig, params),
 		lb:                     metadata.NewLogsBuilder(cfg.LogsBuilderConfig, params),
 		cache:                  cache,
+		planCache:              planCache,
 		lastExecutionTimestamp: time.Unix(0, 0),
 		obfuscator:             newObfuscator(),
 		serviceInstanceID:      serviceInstanceID,
@@ -685,6 +688,7 @@ func (s *sqlServerScraperHelper) recordDatabaseQueryTextAndPlan(ctx context.Cont
 	now := time.Now()
 	timestamp := pcommon.NewTimestampFromTime(now)
 	s.lastExecutionTimestamp = now
+	s.logger.Debug("Current planCache size: " + strconv.Itoa(s.planCache.Len()))
 	for i, row := range rows {
 		// skipping the rest of the rows as totalElapsedTimeDiffs is sorted in descending order
 		if totalElapsedTimeDiffsMicrosecond[i] == 0 {
@@ -696,6 +700,8 @@ func (s *sqlServerScraperHelper) recordDatabaseQueryTextAndPlan(ctx context.Cont
 		queryHashVal := hex.EncodeToString([]byte(row[queryHash]))
 		queryPlanHashVal := hex.EncodeToString([]byte(row[queryPlanHash]))
 
+		isNewPlan := s.cacheIfNewPlan(queryHashVal, queryPlanHashVal)
+
 		queryTextVal := s.retrieveValue(row, queryText, &errs, func(row sqlquery.StringMap, columnName string) (any, error) {
 			statement := row[columnName]
 			obfuscated, err := s.obfuscator.obfuscateSQLString(statement)
@@ -731,9 +737,12 @@ func (s *sqlServerScraperHelper) recordDatabaseQueryTextAndPlan(ctx context.Cont
 			physicalReadsVal = int64(0)
 		}
 
-		queryPlanVal := s.retrieveValue(row, queryPlan, &errs, func(row sqlquery.StringMap, columnName string) (any, error) {
-			return s.obfuscator.obfuscateXMLPlan(row[columnName])
-		})
+		var queryPlanVal any = ""
+		if isNewPlan {
+			queryPlanVal = s.retrieveValue(row, queryPlan, &errs, func(row sqlquery.StringMap, columnName string) (any, error) {
+				return s.obfuscator.obfuscateXMLPlan(row[columnName])
+			})
+		}
 
 		rowsReturnedVal := s.retrieveValue(row, rowsReturned, &errs, retrieveInt)
 		cached, rowsReturnedVal = s.cacheAndDiff(queryHashVal, queryPlanHashVal, rowsReturned, rowsReturnedVal.(int64))
@@ -787,6 +796,15 @@ func (s *sqlServerScraperHelper) recordDatabaseQueryTextAndPlan(ctx context.Cont
 	return resources, errors.Join(errs...)
 }
 
+func (s *sqlServerScraperHelper) cacheIfNewPlan(queryHashVal string, queryPlanHashVal string) bool {
+	cachedPlanHashValue, isPlanHashPresent := s.planCache.Get(queryHashVal)
+	if !isPlanHashPresent || cachedPlanHashValue != queryPlanHashVal {
+		s.planCache.Add(queryHashVal, queryPlanHashVal)
+		return true
+	}
+	return false
+}
+
 func (s *sqlServerScraperHelper) retrieveValue(
 	row sqlquery.StringMap,
 	column string,