我们可以从数据库中删除 Memory 优化文件组吗

Question

I checked In sql server 2019(15.0.2070.41) and tried to remove with bellow mentioned command:

Alter database InMemoryCheckpoint 
Remove file InMemoryCheckpointDF 

Alter database InMemoryCheckpoint 
Remove filegroup InMemoryCheckpointDF

Answer 1

You can't remove a memory-optimized filegroup.

The following limitations apply to a memory-optimized filegroup:

Once you use a memory-optimized filegroup, you can only remove it by dropping the database. In a production environment, it is unlikely that you will need to remove the memory-optimized filegroup.

https://docs.microsoft.com/en-us/sql/relational-databases/in-memory-oltp/the-memory-optimized-filegroup?view=sql-server-ver15

Answer 2

!!! Please use this method in case of corrupted database that contains memory optimized table (you can't use DBCC check on databases that contains memory optimized tables) !!!

WARNING: This is an unsupported operation. There have been reports of unrecoverable log corruption when using this.

It's a hack method and it's risky. Microsoft didn't verified this solution

Before doing anything take backup

1- Delete memory optimized tables

2- Detach Database

3- Create new database with same files without memory optimized filegroup

4- Modify database files and change it to detached database (mdf,ldf,ndf) files

alter database test1 modify file (name='test1' , filename='C:\Program Files\Microsoft SQL Server\MSSQL15.MSSQLSERVER\MSSQL\DATA\test.mdf')

alter database test1 modify file (name='test1_log' , filename='C:\Program Files\Microsoft SQL Server\MSSQL15.MSSQLSERVER\MSSQL\DATA\test_log.ldf')

5- Now try to to repair database:

alter database test1 set emergency

alter database test1 set single_user with ROLLBACK IMMEDIATE;

dbcc checkdb(test1,repair_allow_data_loss)

alter database test1 set multi_user

alter database test1 set online

6- After successfully repair database remove memory optimized filegroup from database

ALTER DATABASE [test1] REMOVE FILEGROUP [memory_optimized_filegroup_0]

Follow steps correctly for prevent log corruption

Step 4: Alter log file name must be done correctly Step 5: DBCC is Important to prevent corruption

Also for getting best result:

Don't use database while doing steps (Insert - Update - Changing Schema)

do CHECKPOINT to flush log to data file then shrink log file

you will never have log corruption issue

Don't forget:

Before using your database do this steps for checking issue:

1. Insert or update 1 row in database
2. Do CHECKPOINT
3. Restart server

If database got online i think you did all steps correctly else Restore database from backup and forget about removing memory optimized filegroup

Answer 3

Used these commands and they worked fine for me:

USE [<dbname>]
GO

ALTER DATABASE [<dbname>]  REMOVE FILE [<filename>]
GO

ALTER DATABASE [<dbname>] REMOVE FILEGROUP [<Group Name>]
GO