br: avoid too many warning logs after update schema version (#43416)

close pingcap/tidb#43402

br/pkg/restore/client.go

@@ -3072,8 +3072,20 @@ func (rc *Client) UpdateSchemaVersion(ctx context.Context) error {
 		func(ctx context.Context, txn kv.Transaction) error {
 			t := meta.NewMeta(txn)
 			var e error
-			schemaVersion, e = t.GenSchemaVersions(128)
-			return e
+			// To trigger full-reload instead of diff-reload, we need to increase the schema version
+			// by at least `domain.LoadSchemaDiffVersionGapThreshold`.
+			schemaVersion, e = t.GenSchemaVersions(64 + domain.LoadSchemaDiffVersionGapThreshold)
+			if e != nil {
+				return e
+			}
+			// add the diff key so that the domain won't retry to reload the schemas with `schemaVersion` frequently.
+			return t.SetSchemaDiff(&model.SchemaDiff{
+				Version:             schemaVersion,
+				Type:                model.ActionNone,
+				SchemaID:            -1,
+				TableID:             -1,
+				RegenerateSchemaMap: true,
+			})
 		},
 	); err != nil {
 		return errors.Trace(err)

domain/domain.go

@@ -96,6 +96,9 @@ import (
 
 var (
 	mdlCheckLookDuration = 50 * time.Millisecond
+
+	// LoadSchemaDiffVersionGapThreshold is the threshold for version gap to reload domain by loading schema diffs
+	LoadSchemaDiffVersionGapThreshold int64 = 100
 )
 
 func init() {
@@ -230,7 +233,7 @@ func (do *Domain) loadInfoSchema(startTS uint64) (infoschema.InfoSchema, bool, i
 	// 3. There are less 100 diffs.
 	// 4. No regenrated schema diff.
 	startTime := time.Now()
-	if currentSchemaVersion != 0 && neededSchemaVersion > currentSchemaVersion && neededSchemaVersion-currentSchemaVersion < 100 {
+	if currentSchemaVersion != 0 && neededSchemaVersion > currentSchemaVersion && neededSchemaVersion-currentSchemaVersion < LoadSchemaDiffVersionGapThreshold {
 		is, relatedChanges, err := do.tryLoadSchemaDiffs(m, currentSchemaVersion, neededSchemaVersion)
 		if err == nil {
 			do.infoCache.Insert(is, uint64(schemaTs))
@@ -415,13 +418,13 @@ func (do *Domain) tryLoadSchemaDiffs(m *meta.Meta, usedVersion, newVersion int64
 	phyTblIDs := make([]int64, 0, len(diffs))
 	actions := make([]uint64, 0, len(diffs))
 	for _, diff := range diffs {
+		if diff.RegenerateSchemaMap {
+			return nil, nil, errors.Errorf("Meets a schema diff with RegenerateSchemaMap flag")
+		}
 		IDs, err := builder.ApplyDiff(m, diff)
 		if err != nil {
 			return nil, nil, err
 		}
-		if diff.RegenerateSchemaMap {
-			return nil, nil, errors.Errorf("Meets a schema diff with RegenerateSchemaMap flag")
-		}
 		if canSkipSchemaCheckerDDL(diff.Type) {
 			continue
 		}