Piecemeal Restore of Databases With Memory-Optimized Tables

Applies to: yesSQL Server (all supported versions) YesAzure SQL Database

Piecemeal restore is supported on databases with memory-optimized tables except for one restriction described below. For more information about piecemeal backup and restore, see RESTORE (Transact-SQL) and Piecemeal Restores (SQL Server).

A memory-optimized filegroup must be backed up and restored together with the primary filegroup:

  • If you back up (or restore) the primary filegroup you must specify the memory-optimized filegroup.

  • If you back up (or restore) the memory-optimized filegroup you must specify the primary filegroup.

Key scenarios for piecemeal backup and restore are,

  • Piecemeal backup allows you to reduce the size of backup. Some examples:

    • Configure the database backup to occur at different times or days to minimize the impact on the workload. One example is a very large database (greater than 1 TB) where a full database backup cannot complete in the time allocated for database maintenance. In that situation, you can use piecemeal backup to backup the full database in multiple piecemeal backups.

    • If a filegroup is marked read-only, it does not require a transaction log backup after it was marked read-only. You can choose to back up the filegroup only once after marking it read-only.

  • Piecemeal restore.

    • The goal of a piecemeal restore is to bring the critical parts of database online without waiting for all the data. One example is if a database has partitioned data, such that older partitions are only used rarely. You can restore them only on an as-needed basis. Similar for filegroups that contain, for example, historical data.

    • Using page repair, you can fix page corruption by specifically restoring the page. For more information, see Restore Pages (SQL Server).

Samples

The examples use the following schema:

CREATE DATABASE imoltp
    ON PRIMARY (
        name = imoltp_primary1,
        filename = 'c:\data\imoltp_data1.mdf')
    LOG ON (
        name = imoltp_log,
        filename = 'c:\data\imoltp_log.ldf');
    GO  
  
ALTER DATABASE imoltp
    ADD FILE (
        name = imoltp_primary2,
        filename = 'c:\data\imoltp_data2.ndf');
GO  
  
ALTER DATABASE imoltp
    ADD FILEGROUP imoltp_secondary;

ALTER DATABASE imoltp
    ADD FILE (
        name = imoltp_secondary,
        filename = 'c:\data\imoltp_secondary.ndf')
            TO FILEGROUP imoltp_secondary;
GO  
  
ALTER DATABASE imoltp
    ADD FILEGROUP imoltp_mod
    CONTAINS MEMORY_OPTIMIZED_DATA;

ALTER DATABASE imoltp
    ADD FILE (
        name = 'imoltp_mod1',
        filename = 'c:\data\imoltp_mod1')
            TO FILEGROUP imoltp_mod;

ALTER DATABASE imoltp
    ADD FILE (
        name = 'imoltp_mod2',
        filename = 'c:\data\imoltp_mod2')
            TO FILEGROUP imoltp_mod;
GO  

Backup

This sample shows how to back up the primary filegroup and the memory-optimized filegroup. You must specify both primary and memory-optimized filegroup together.

BACKUP database imoltp
    filegroup = 'primary',
    filegroup = 'imoltp_mod'
    to disk = 'c:\data\imoltp.dmp'
    with init;

The following sample shows that a backup of a filegroup other than primary, and memory-optimized filegroup, works similar to the databases without memory-optimized tables. The following command backs up the secondary filegroup

BACKUP database imoltp
    filegroup = 'imoltp_secondary'
    to disk = 'c:\data\imoltp_secondary.dmp'
    with init;

Restore

The following sample shows how to restore the primary filegroup and memory-optimized filegroup together.

RESTORE database imoltp
    filegroup = 'primary',
    filegroup = 'imoltp_mod'
    from disk = 'c:\data\imoltp.dmp'
    with
        partial,
        norecovery;

-- Restore the transaction log.

RESTORE LOG [imoltp]
    FROM DISK = N'c:\data\imoltp_log.dmp'
    WITH
        FILE = 1,
        NOUNLOAD,
        STATS = 10;
GO

The next sample shows that restoring filegroup(s) other than the primary and memory-optimized filegroup works similar to the databases without memory-optimized tables

RESTORE DATABASE [imoltp]
    FILE = N'imoltp_secondary'
    FROM DISK = N'c:\data\imoltp_secondary.dmp'
    WITH
        FILE = 1,
        RECOVERY,
        NOUNLOAD,
        STATS = 10;
GO

See Also

Backup, Restore, and Recovery of Memory-Optimized Tables