ClickHouse/docs/en/operations/system-tables/backup_log.md

slug
/en/operations/system-tables/backup_log

backup_log

Contains logging entries with the information about BACKUP and RESTORE operations.

Columns:

• hostname (LowCardinality(String)) — Hostname of the server executing the query.
• event_date (Date) — Date of the entry.
• event_time (DateTime) — The date and time of the entry.
• event_time_microseconds (DateTime64) — Time of the entry with microseconds precision.
• id (String) — Identifier of the backup or restore operation.
• name (String) — Name of the backup storage (the contents of the FROM or TO clause).
• status (Enum8) — Operation status. Possible values:
  • 'CREATING_BACKUP'
  • 'BACKUP_CREATED'
  • 'BACKUP_FAILED'
  • 'RESTORING'
  • 'RESTORED'
  • 'RESTORE_FAILED'
• error (String) — Error message of the failed operation (empty string for successful operations).
• start_time (DateTime) — Start time of the operation.
• end_time (DateTime) — End time of the operation.
• num_files (UInt64) — Number of files stored in the backup.
• total_size (UInt64) — Total size of files stored in the backup.
• num_entries (UInt64) — Number of entries in the backup, i.e. the number of files inside the folder if the backup is stored as a folder, or the number of files inside the archive if the backup is stored as an archive. It is not the same as num_files if it's an incremental backup or if it contains empty files or duplicates. The following is always true: num_entries <= num_files.
• uncompressed_size (UInt64) — Uncompressed size of the backup.
• compressed_size (UInt64) — Compressed size of the backup. If the backup is not stored as an archive it equals to uncompressed_size.
• files_read (UInt64) — Number of files read during the restore operation.
• bytes_read (UInt64) — Total size of files read during the restore operation.

Example

BACKUP TABLE test_db.my_table TO Disk('backups_disk', '1.zip')

┌─id───────────────────────────────────┬─status─────────┐
│ e5b74ecb-f6f1-426a-80be-872f90043885 │ BACKUP_CREATED │
└──────────────────────────────────────┴────────────────┘

SELECT * FROM system.backup_log WHERE id = 'e5b74ecb-f6f1-426a-80be-872f90043885' ORDER BY event_date, event_time_microseconds \G

Row 1:
──────
hostname:                clickhouse.eu-central1.internal
event_date:              2023-08-19
event_time_microseconds: 2023-08-19 11:05:21.998566
id:                      e5b74ecb-f6f1-426a-80be-872f90043885
name:                    Disk('backups_disk', '1.zip')
status:                  CREATING_BACKUP
error:                   
start_time:              2023-08-19 11:05:21
end_time:                1970-01-01 03:00:00
num_files:               0
total_size:              0
num_entries:             0
uncompressed_size:       0
compressed_size:         0
files_read:              0
bytes_read:              0

Row 2:
──────
hostname:                clickhouse.eu-central1.internal
event_date:              2023-08-19
event_time:              2023-08-19 11:08:56
event_time_microseconds: 2023-08-19 11:08:56.916192
id:                      e5b74ecb-f6f1-426a-80be-872f90043885
name:                    Disk('backups_disk', '1.zip')
status:                  BACKUP_CREATED
error:                   
start_time:              2023-08-19 11:05:21
end_time:                2023-08-19 11:08:56
num_files:               57
total_size:              4290364870
num_entries:             46
uncompressed_size:       4290362365
compressed_size:         3525068304
files_read:              0
bytes_read:              0

RESTORE TABLE test_db.my_table FROM Disk('backups_disk', '1.zip')

┌─id───────────────────────────────────┬─status───┐
│ cdf1f731-52ef-42da-bc65-2e1bfcd4ce90 │ RESTORED │
└──────────────────────────────────────┴──────────┘

SELECT * FROM system.backup_log WHERE id = 'cdf1f731-52ef-42da-bc65-2e1bfcd4ce90' ORDER BY event_date, event_time_microseconds \G

Row 1:
──────
hostname:                clickhouse.eu-central1.internal
event_date:              2023-08-19
event_time_microseconds: 2023-08-19 11:09:19.718077
id:                      cdf1f731-52ef-42da-bc65-2e1bfcd4ce90
name:                    Disk('backups_disk', '1.zip')
status:                  RESTORING
error:                   
start_time:              2023-08-19 11:09:19
end_time:                1970-01-01 03:00:00
num_files:               0
total_size:              0
num_entries:             0
uncompressed_size:       0
compressed_size:         0
files_read:              0
bytes_read:              0

Row 2:
──────
hostname:                clickhouse.eu-central1.internal
event_date:              2023-08-19
event_time_microseconds: 2023-08-19 11:09:29.334234
id:                      cdf1f731-52ef-42da-bc65-2e1bfcd4ce90
name:                    Disk('backups_disk', '1.zip')
status:                  RESTORED
error:                   
start_time:              2023-08-19 11:09:19
end_time:                2023-08-19 11:09:29
num_files:               57
total_size:              4290364870
num_entries:             46
uncompressed_size:       4290362365
compressed_size:         4290362365
files_read:              57
bytes_read:              4290364870

This is essentially the same information that is written in the system table system.backups:

SELECT * FROM system.backups ORDER BY start_time

┌─id───────────────────────────────────┬─name──────────────────────────┬─status─────────┬─error─┬──────────start_time─┬────────────end_time─┬─num_files─┬─total_size─┬─num_entries─┬─uncompressed_size─┬─compressed_size─┬─files_read─┬─bytes_read─┐
│ e5b74ecb-f6f1-426a-80be-872f90043885 │ Disk('backups_disk', '1.zip') │ BACKUP_CREATED │       │ 2023-08-19 11:05:21 │ 2023-08-19 11:08:56 │        57 │ 4290364870 │          46 │        4290362365 │      3525068304 │          0 │          0 │
│ cdf1f731-52ef-42da-bc65-2e1bfcd4ce90 │ Disk('backups_disk', '1.zip') │ RESTORED       │       │ 2023-08-19 11:09:19 │ 2023-08-19 11:09:29 │        57 │ 4290364870 │          46 │        4290362365 │      4290362365 │         57 │ 4290364870 │
└──────────────────────────────────────┴───────────────────────────────┴────────────────┴───────┴─────────────────────┴─────────────────────┴───────────┴────────────┴─────────────┴───────────────────┴─────────────────┴────────────┴────────────┘

See Also

• Backup and Restore