metrics,planner: add 'pseudo estimation' reason in the metrics (#21911)

pingcap · Jan 4, 2021 · b45fa8b · b45fa8b
1 parent afcf637
commit b45fa8b
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Showing 3 changed files with 11 additions and 5 deletions.
diff --git a/metrics/grafana/tidb.json b/metrics/grafana/tidb.json
@@ -9673,10 +9673,10 @@
           "steppedLine": false,
           "targets": [
             {
-              "expr": "sum(rate(tidb_statistics_pseudo_estimation_total[1m]))",
+              "expr": "sum(rate(tidb_statistics_pseudo_estimation_total[30s])) by (type)",
               "format": "time_series",
               "intervalFactor": 2,
-              "legendFormat": "Pseudo OPS",
+              "legendFormat": "{{type}}",
               "refId": "A",
               "step": 30
             }

diff --git a/metrics/stats.go b/metrics/stats.go
@@ -45,13 +45,13 @@ var (
 			Buckets:   prometheus.ExponentialBuckets(0.01, 2, 14),
 		})
 
-	PseudoEstimation = prometheus.NewCounter(
+	PseudoEstimation = prometheus.NewCounterVec(
 		prometheus.CounterOpts{
 			Namespace: "tidb",
 			Subsystem: "statistics",
 			Name:      "pseudo_estimation_total",
 			Help:      "Counter of pseudo estimation caused by outdated stats.",
-		})
+		}, []string{LblType})
 
 	DumpFeedbackCounter = prometheus.NewCounterVec(
 		prometheus.CounterOpts{

diff --git a/planner/core/logical_plan_builder.go b/planner/core/logical_plan_builder.go
@@ -3497,6 +3497,11 @@ func (ds *DataSource) newExtraHandleSchemaCol() *expression.Column {
 	}
 }
 
+var (
+	pseudoEstimationNotAvailable = metrics.PseudoEstimation.WithLabelValues("nodata")
+	pseudoEstimationOutdate      = metrics.PseudoEstimation.WithLabelValues("outdate")
+)
+
 // getStatsTable gets statistics information for a table specified by "tableID".
 // A pseudo statistics table is returned in any of the following scenario:
 // 1. tidb-server started and statistics handle has not been initialized.
@@ -3519,6 +3524,7 @@ func getStatsTable(ctx sessionctx.Context, tblInfo *model.TableInfo, pid int64)
 
 	// 2. table row count from statistics is zero.
 	if statsTbl.Count == 0 {
+		pseudoEstimationNotAvailable.Inc()
 		return statistics.PseudoTable(tblInfo)
 	}
 
@@ -3527,7 +3533,7 @@ func getStatsTable(ctx sessionctx.Context, tblInfo *model.TableInfo, pid int64)
 		tbl := *statsTbl
 		tbl.Pseudo = true
 		statsTbl = &tbl
-		metrics.PseudoEstimation.Inc()
+		pseudoEstimationOutdate.Inc()
 	}
 	return statsTbl
 }