Merge #35552

35552: sql/stats: read the list of initial tables asynchronously r=knz a=knz Recommended by @RaduBerinde and @bdarnell in #35549 This patch changes the refresher init code to perform the initial scan through all descriptors using ASOT, to avoid possible txn conflicts with the first client connections (or tests). Release note: None Co-authored-by: Raphael 'kena' Poss <[email protected]>
cockroachdb · Mar 9, 2019 · efc57fa · efc57fa
2 parents 38bb1e7 + 2a078b9
commit efc57fa
Showing 1 changed file with 17 additions and 6 deletions.
diff --git a/pkg/sql/stats/automatic_stats.go b/pkg/sql/stats/automatic_stats.go
@@ -192,10 +192,6 @@ func (r *Refresher) Start(
 	ctx context.Context, st *settings.Values, stopper *stop.Stopper, refreshInterval time.Duration,
 ) error {
 	stopper.RunWorker(context.Background(), func(ctx context.Context) {
-		// Ensure that read-only tables will have stats created at least once
-		// on startup.
-		r.ensureAllTables(ctx, st)
-
 		// We always sleep for r.asOfTime at the beginning of each refresh, so
 		// subtract it from the refreshInterval.
 		refreshInterval -= r.asOfTime
@@ -206,8 +202,16 @@ func (r *Refresher) Start(
 		timer := time.NewTimer(refreshInterval)
 		defer timer.Stop()
 
+		// Ensure that read-only tables will have stats created at least
+		// once on startup.
+		const initialTableCollectionDelay = time.Second
+		initialTableCollection := time.After(initialTableCollectionDelay)
+
 		for {
 			select {
+			case <-initialTableCollection:
+				r.ensureAllTables(ctx, st, initialTableCollectionDelay)
+
 			case <-timer.C:
 				mutationCounts := r.mutationCounts
 				if err := stopper.RunAsyncTask(
@@ -259,17 +263,24 @@ func (r *Refresher) Start(
 
 // ensureAllTables ensures that an entry exists in r.mutationCounts for each
 // table in the database.
-func (r *Refresher) ensureAllTables(ctx context.Context, settings *settings.Values) {
+func (r *Refresher) ensureAllTables(
+	ctx context.Context, settings *settings.Values, initialTableCollectionDelay time.Duration,
+) {
 	if !AutomaticStatisticsClusterMode.Get(settings) {
 		// Automatic stats are disabled.
 		return
 	}
 
+	// Use a historical read so as to disable txn contention resolution.
+	getAllTablesQuery := fmt.Sprintf(
+		`SELECT table_id FROM crdb_internal.tables AS OF SYSTEM TIME '-%s'`,
+		initialTableCollectionDelay)
+
 	rows, err := r.ex.Query(
 		ctx,
 		"get-tables",
 		nil, /* txn */
-		`SELECT table_id FROM crdb_internal.tables;`,
+		getAllTablesQuery,
 	)
 	if err != nil {
 		log.Errorf(ctx, "failed to get tables for automatic stats: %v", err)