planner: quickly get total count from index/column (#58365)

close #58366

pkg/planner/cardinality/ndv.go

@@ -51,13 +51,18 @@ func getTotalRowCount(statsTbl *statistics.Table, colHist *statistics.Column) in
 	}
 	// If colHist is not fully loaded, we may still get its total row count from other index/column stats.
 	totCount := int64(0)
+	stop := false
 	statsTbl.ForEachIndexImmutable(func(_ int64, idx *statistics.Index) bool {
 		if idx.IsFullLoad() && idx.LastUpdateVersion == colHist.LastUpdateVersion {
 			totCount = int64(idx.TotalRowCount())
+			stop = true
 			return true
 		}
 		return false
 	})
+	if stop {
+		return totCount
+	}
 	statsTbl.ForEachColumnImmutable(func(_ int64, col *statistics.Column) bool {
 		if col.IsFullLoad() && col.LastUpdateVersion == colHist.LastUpdateVersion {
 			totCount = int64(col.TotalRowCount())