Please answer these questions before submitting your issue. Thanks!

1. What did you do?
   If possible, provide a recipe for reproducing the error.

2. Import some data (5GB) to table test.oomtest, and there is no user created tables in mysql schema

3. Do full backup

4. Do br restore, and specify -f "mysql.*" parameter to restore system tables only

5. What did you expect to see?

• no tables should be restored, as there is no user created tables in mysql schema, and restore statistics should be accurate.

3. What did you see instead?

• Restore statistics not accurate, 7.426GB seems the backup size, not the restored data size.
• Also, it seems that restore statistics is not correctly when restore part of the backup. (for example, there are 2 tables in backup, and restore only one tables.)

[2021/06/23 01:56:29.793 -04:00] [INFO] [collector.go:66] ["Full restore success summary"] [total-ranges=44] [ranges-succeed=44] [ranges-failed=0] [split-region=601.358689ms] [restore-checksum=43.793886ms] [restore-ranges=19] [total-take=6.156156669s] ["restore data size(after decompressed)"=7.426GB] [total-kv=3345] [total-kv-size=287kB] [average-speed=584.5kB/s]

[root@localhost v5.1.0]# ./br restore full --pd "172.16.6.226:2379" --storage "s3://nfs/fubin/br0623?access-key=minioadmin&secret-access-key=minioadmin&endpoint=http%3a%2f%2fminio.pingcap.net%3a9000&force-path-style=true" --send-credentials-to-tikv=true -f "mysql*.*" --log-file restore.system.2.log
Detail BR log in restore.system.2.log
Full restore <---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|> 100.00%[2021/06/23 01:56:29.111 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring stats via mysql schema isn't support yet: the table ID is out-of-date and may corrupt existing statistics"] [table=stats_meta]
[2021/06/23 01:56:29.111 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring stats via mysql schema isn't support yet: the table ID is out-of-date and may corrupt existing statistics"] [table=stats_buckets]
[2021/06/23 01:56:29.115 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring unsupported mysql schema table"] [table=gc_delete_range_done]
[2021/06/23 01:56:29.117 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring stats via mysql schema isn't support yet: the table ID is out-of-date and may corrupt existing statistics"] [table=stats_feedback]
[2021/06/23 01:56:29.117 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring unsupported mysql schema table"] [table=schema_index_usage]
[2021/06/23 01:56:29.117 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring unsupported mysql schema table"] [table=gc_delete_range]
[2021/06/23 01:56:29.117 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring unsupported mysql schema table"] [table=default_roles]
[2021/06/23 01:56:29.133 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring unsupported mysql schema table"] [table=columns_priv]
[2021/06/23 01:56:29.134 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring unsupported mysql schema table"] [table=GLOBAL_VARIABLES]
[2021/06/23 01:56:29.134 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring unsupported mysql schema table"] [table=db]
[2021/06/23 01:56:29.134 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring stats via mysql schema isn't support yet: the table ID is out-of-date and may corrupt existing statistics"] [table=stats_extended]
[2021/06/23 01:56:29.134 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring unsupported mysql schema table"] [table=tables_priv]
[2021/06/23 01:56:29.134 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring unsupported mysql schema table"] [table=tidb]
[2021/06/23 01:56:29.149 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring unsupported mysql schema table"] [table=role_edges]
[2021/06/23 01:56:29.149 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring stats via mysql schema isn't support yet: the table ID is out-of-date and may corrupt existing statistics"] [table=stats_histograms]
[2021/06/23 01:56:29.149 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring unsupported mysql schema table"] [table=global_priv]
[2021/06/23 01:56:29.149 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring stats via mysql schema isn't support yet: the table ID is out-of-date and may corrupt existing statistics"] [table=stats_fm_sketch]
[2021/06/23 01:56:29.149 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring unsupported mysql schema table"] [table=user]
[2021/06/23 01:56:29.149 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring unsupported mysql schema table"] [table=global_grants]
[2021/06/23 01:56:29.150 -04:00] [WARN] [systable_restore.go:94] ["error during merging temporary tables into system tables"] [error="[BR:Restore:ErrUnsupportedSysTable]restoring stats via mysql schema isn't support yet: the table ID is out-of-date and may corrupt existing statistics"] [table=stats_top_n]
[2021/06/23 01:56:29.150 -04:00] [WARN] [systable_restore.go:104] ["error during reconfigurating the system tables"] [database=mysql] [error="restored user info may not take effect, until you should execute FLUSH PRIVILEGES manually: [BR:Restore:ErrUnsupportedSysTable]the system table isn't supported for restoring yet"]
Full restore <----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------> 100.00%
[2021/06/23 01:56:29.793 -04:00] [INFO] [collector.go:66] ["Full restore success summary"] [total-ranges=44] [ranges-succeed=44] [ranges-failed=0] [split-region=601.358689ms] [restore-checksum=43.793886ms] [restore-ranges=19] [total-take=6.156156669s] ["restore data size(after decompressed)"=7.426GB] [total-kv=3345] [total-kv-size=287kB] [average-speed=584.5kB/s]

4. What version of BR and TiDB/TiKV/PD are you using?

5. Operation logs

   • Please upload br.log for BR if possible
   • Please upload tidb-lightning.log for TiDB-Lightning if possible
   • Please upload tikv-importer.log from TiKV-Importer if possible
   • Other interesting logs
     restore.system.2.log

6. Configuration of the cluster and the task

   • tidb-lightning.toml for TiDB-Lightning if possible
   • tikv-importer.toml for TiKV-Importer if possible
   • topology.yml if deployed by TiUP

7. Screenshot/exported-PDF of Grafana dashboard or metrics' graph in Prometheus if possible