RESTORE statements - HEADERONLY (Transact-SQL)

Artikkeli
05/10/2023

Applies to: SQL Server Azure SQL Managed Instance

Returns a result set containing all the backup header information for all backup sets on a particular backup device in SQL Server.

Note

For the descriptions of the arguments, see RESTORE Arguments (Transact-SQL).

Transact-SQL syntax conventions

Syntax

RESTORE HEADERONLY
FROM <backup_device>
[ WITH
    {
    -- Backup set options
    FILE = { backup_set_file_number | @backup_set_file_number }
    | PASSWORD = { password | @password_variable }
    | [ METADATA_ONLY | SNAPSHOT ] [ DBNAME = { database_name | @database_name_variable } ]

    -- Media set options
    | MEDIANAME = { media_name | @media_name_variable }
    | MEDIAPASSWORD = { mediapassword | @mediapassword_variable }

    -- Error management options
    | { CHECKSUM | NO_CHECKSUM }
    | { STOP_ON_ERROR | CONTINUE_AFTER_ERROR }

    -- Tape options
    | { REWIND | NOREWIND }
    | { UNLOAD | NOUNLOAD }
    } [ , ...n ]
]
[ ; ]

<backup_device> ::=
{
   { logical_backup_device_name |
     @logical_backup_device_name_var }
   | { DISK | TAPE | URL } = { 'physical_backup_device_name' |
       @physical_backup_device_name_var }
}

Note

URL is the format used to specify the location and the file name for Azure Blob Storage and is supported starting with SQL Server 2012 (11.x) SP 1 CU 2. Although Azure storage is a service, the implementation is similar to disk and tape, to allow for a consistent and seamless restore experience for all the three devices.

Arguments

For descriptions of the RESTORE HEADERONLY arguments, see RESTORE Arguments (Transact-SQL).

Result sets

For each backup on a given device, the server sends a row of header information with the following columns:

Column name	Data type	Description for SQL Server backup sets
`BackupName` ¹	nvarchar(128)	Backup set name.
`BackupDescription`	nvarchar(255)	Backup set description. Can be NULL.
`BackupType`	smallint	Backup type: 1 = Database 2 = Transaction log 4 = File 5 = Differential database 6 = Differential file 7 = Partial 8 = Differential partial
`ExpirationDate`	datetime	Expiration date for the backup set.
`Compressed`	bit	Whether the backup set is compressed using software-based compression: 0 = No 1 = Yes
`Position`	smallint	Position of the backup set in the volume (for use with the FILE = option).
`DeviceType`	tinyint	Number corresponding to the device used for the backup operation. Disk: - 2 = Logical - 102 = Physical Tape: - 5 = Logical - 105 = Physical Virtual Device: - 7 = Logical - 107 = Physical URL: - 9 = Logical - 109 = Physical Logical device names and device numbers are in `sys.backup_devices`. For more information, see sys.backup_devices.
`UserName`	nvarchar(128)	User name that performed the backup operation.
`ServerName`	nvarchar(128)	Name of the server that wrote the backup set.
`DatabaseName`	nvarchar(128)	Name of the database that was backed up.
`DatabaseVersion`	int	Version of the database from which the backup was created.
`DatabaseCreationDate`	datetime	Date and time the database was created.
`BackupSize`	numeric(20,0)	Size of the backup, in bytes.
`FirstLSN`	numeric(25,0)	Log sequence number of the first log record in the backup set.
`LastLSN`	numeric(25,0)	Log sequence number of the next log record after the backup set.
`CheckpointLSN`	numeric(25,0)	Log sequence number of the most recent checkpoint at the time the backup was created.
`DatabaseBackupLSN`	numeric(25,0)	Log sequence number of the most recent full database backup. `DatabaseBackupLSN` is the "begin of checkpoint" that is triggered when the backup starts. This LSN coincides with `FirstLSN` if the backup is taken when the database is idle and no replication is configured.
`BackupStartDate`	datetime	Date and time that the backup operation began.
`BackupFinishDate`	datetime	Date and time that the backup operation finished.
`SortOrder`	smallint	Server sort order. This column is valid for database backups only. Provided for backward compatibility.
`CodePage`	smallint	Server code page or character set used by the server.
`UnicodeLocaleId`	int	Server Unicode locale ID configuration option used for Unicode character data sorting. Provided for backward compatibility.
`UnicodeComparisonStyle`	int	Server Unicode comparison style configuration option, which provides additional control over the sorting of Unicode data. Provided for backward compatibility.
`CompatibilityLevel`	tinyint	Compatibility level setting of the database from which the backup was created.
`SoftwareVendorId`	int	Software vendor identification number. For SQL Server, this number is `4608` (or hexadecimal `0x1200`).
`SoftwareVersionMajor`	int	Major version number of the server that created the backup set.
`SoftwareVersionMinor`	int	Minor version number of the server that created the backup set.
`SoftwareVersionBuild`	int	Build number of the server that created the backup set.
`MachineName`	nvarchar(128)	Name of the computer that performed the backup operation.
`Flags`	int	Individual flags bit meanings: - 1 = Log backup contains bulk-logged operations. - 2 = Snapshot backup. - 4 = Database was read-only when backed up. - 8 = Database was in single-user mode when backed up. - 16 = Backup contains backup checksums. - 32 = Database was damaged when backed up, but the backup operation was requested to continue despite errors. - 64 = Tail log backup. - 128 = Tail log backup with incomplete metadata. - 256 = Tail log backup with NORECOVERY. Important: We recommend that instead of `Flags` you use the individual Boolean columns (starting with `HasBulkLoggedData` and ending with `IsCopyOnly` in this table).
`BindingID`	uniqueidentifier	Binding ID for the database. This value corresponds to `database_guid` in `sys.database_recovery_status`. When a database is restored, a new value is assigned. Also see `FamilyGUID`.
`RecoveryForkID`	uniqueidentifier	ID for the ending recovery fork. This column corresponds to `last_recovery_fork_guid` in the backupset table. For data backups, `RecoveryForkID` equals `FirstRecoveryForkID`.
`Collation`	nvarchar(128)	Collation used by the database.
`FamilyGUID`	uniqueidentifier	ID of the original database when created. This value stays the same when the database is restored.
`HasBulkLoggedData`	bit	1 = Log backup containing bulk-logged operations.
`IsSnapshot`	bit	1 = Snapshot backup.
`IsReadOnly`	bit	1 = Database was read-only when backed up.
`IsSingleUser`	bit	1 = Database was single-user when backed up.
`HasBackupChecksums`	bit	1 = Backup contains backup checksums.
`IsDamaged`	bit	1 = Database was damaged when backed up, but the backup operation was requested to continue despite errors.
`BeginsLogChain`	bit	1 = This is the first in a continuous chain of log backups. A log chain begins with the first log backup taken after the database is created or when it is switched from the Simple to the Full or Bulk-Logged recovery model.
`HasIncompleteMetaData`	bit	1 = A tail-log backup with incomplete metadata. For information about tail-log backups with incomplete backup metadata, see Tail-Log Backups (SQL Server).
`IsForceOffline`	bit	1 = Backup taken with NORECOVERY; the database was taken offline by backup.
`IsCopyOnly`	bit	1 = A copy-only backup. A copy-only backup doesn't affect the overall backup and restore procedures for the database. For more information, see Copy-Only Backups (SQL Server).
`FirstRecoveryForkID`	uniqueidentifier	ID for the starting recovery fork. This column corresponds to `first_recovery_fork_guid` in the backupset table. For data backups, `FirstRecoveryForkID` equals `RecoveryForkID`.
`ForkPointLSN`	numeric(25,0)	If `FirstRecoveryForkID` isn't equal to `RecoveryForkID`, this value is the log sequence number of the fork point. Otherwise, this value is NULL.
`RecoveryModel`	nvarchar(60)	Recovery model for the database, one of: - FULL - BULK-LOGGED - SIMPLE
`DifferentialBaseLSN`	numeric(25,0)	For a single-based differential backup, the value equals the `FirstLSN` of the differential base. Changes with LSNs greater than or equal to `DifferentialBaseLSN` are included in the differential. For a multi-based differential, the value is NULL, and the base LSN must be determined at the file level. For more information, see RESTORE FILELISTONLY. For non-differential backup types, the value is always NULL. For more information, see Differential Backups (SQL Server).
`DifferentialBaseGUID`	uniqueidentifier	For a single-based differential backup, the value is the unique identifier of the differential base. For multi-based differentials, the value is NULL, and the differential base must be determined per file. For non-differential backup types, the value is NULL.
`BackupTypeDescription`	nvarchar(60)	Backup type as string, one of: - DATABASE - TRANSACTION LOG - FILE OR FILEGROUP - DATABASE DIFFERENTIAL - FILE DIFFERENTIAL PARTIAL - PARTIAL DIFFERENTIAL
`BackupSetGUID`	uniqueidentifier	Unique identification number of the backup set, by which it is identified on the media. Can be NULL.
`CompressedBackupSize`	bigint	Byte count of the backup set. For uncompressed backups, this value is the same as `BackupSize`. To calculate the compression ratio, use `CompressedBackupSize` and `BackupSize`. During an `msdb` upgrade, this value is set to match the value of the `BackupSize` column.
`containment`	tinyint	Applies to: SQL Server 2012 (11.x) and later versions. Indicates the containment status of the database. 0 = database containment is off 1 = database is in partial containment
`KeyAlgorithm`	nvarchar(32)	Applies to: SQL Server 2014 (12.x) CU 1 and later versions. The encryption algorithm used to encrypt the backup. NO_Encryption indicates that the backup wasn't encrypted. When the correct value can't be determined the value should be NULL.
`EncryptorThumbprint`	varbinary(20)	Applies to: SQL Server 2014 (12.x) CU 1 and later versions. The thumbprint of the encryptor that can be used to find certificate or the asymmetric key in the database. When the backup wasn't encrypted, this value is NULL.
`EncryptorType`	nvarchar(32)	Applies to: SQL Server 2014 (12.x) CU 1 and later versions. The type of encryptor used: Certificate or Asymmetric Key. When the backup wasn't encrypted, this value is NULL.
`LastValidRestoreTime`	datetime	Applies to: SQL Server 2022 (16.x) and later versions. The last valid restore time.
`TimeZone`	nvarchar(32)	Applies to: SQL Server 2022 (16.x) and later versions. The time zone of the server from which the backup was taken.
`CompressionAlgorithm`	nvarchar(32)	Applies to: SQL Server 2022 (16.x) and later versions. Identifies the compression algorithm used to compress the backup file. Default is MS_XPRESS. For more information, see BACKUP.

¹ If passwords are defined for the backup sets, RESTORE HEADERONLY shows complete information for only the backup set whose password matches the specified PASSWORD option of the command. RESTORE HEADERONLY also shows complete information for unprotected backup sets. The BackupName column for the other password-protected backup sets on the media is set to 'Password Protected', and all other columns are NULL.

Remarks

A client can use RESTORE HEADERONLY to retrieve all the backup header information for all backups on a particular backup device. For each backup on the backup device, the server sends the header information as a row.

RESTORE HEADERONLY looks at all backup sets on the media. Therefore, producing this result set when using high-capacity tape drives can take some time. To get a quick look at the media without getting information about every backup set, use RESTORE LABELONLY or specify FILE = <backup_set_file_number>.

Owing to the nature of Microsoft Tape Format, it is possible for backup sets from other software programs to occupy space on the same media as SQL Server backup sets. The result set returned by RESTORE HEADERONLY includes a row for each of these other backup sets.

Security

A backup operation may optionally specify passwords for a media set, a backup set, or both. When a password has been defined on a media set or backup set, you must specify the correct password or passwords in the RESTORE statement. These passwords prevent unauthorized restore operations and unauthorized appends of backup sets to media using SQL Server tools. However, a password doesn't prevent overwrite of media using the BACKUP statement's FORMAT option.

Important

The protection provided by this password is weak. It is intended to prevent an incorrect restore using SQL Server tools by authorized or unauthorized users. It does not prevent the reading of the backup data by other means or the replacement of the password. This feature will be removed in a future version of SQL Server. Avoid using this feature in new development work, and plan to modify applications that currently use this feature.The best practice for protecting backups is to store backup tapes in a secure location or back up to disk files that are protected by adequate access control lists (ACLs). The ACLs should be set on the directory root under which backups are created.

Permissions

Obtaining information about a backup set or backup device requires CREATE DATABASE permission. For more information, see GRANT Database Permissions (Transact-SQL).

Examples

The following example returns the information in the header for the disk file C:\AdventureWorks-FullBackup.bak.

RESTORE HEADERONLY
FROM DISK = N'C:\AdventureWorks-FullBackup.bak';
GO

Jaa