Permissions for truncating a table

Question

What permission do I need to GRANT a user, in MSSQL, in order to be able to truncate a table?

I'm trying to grant the minimal set of permissions, but I can't use DELETE, because the table is very large, and I want the operation to be quick.

Answer 1

You need the ALTER permission: see the Permissions section here.

Note that you can also use a stored procedure with EXECUTE AS, so that the user running the stored procedure does not need to even be granted the ALTER permission.

Answer 2

The minimum permission required is ALTER on table_name. TRUNCATE TABLE permissions default to the table owner, members of the sysadmin fixed server role, and the db_owner and db_ddladmin fixed database roles, and are not transferable. However, you can incorporate the TRUNCATE TABLE statement within a module, such as a stored procedure, and grant appropriate permissions to the module using the EXECUTE AS clause. For more information, see Using EXECUTE AS to Create Custom Permission Sets.

Source

Answer 3

You can create a stored procedure with execute as owner:

create procedure dbo.TruncTable
with execute as owner
as
truncate table TheTable
go

Then grant execution permissions to whoever needs to truncate that table:

grant execute on TruncTable to TheUser

Now TheUser can truncate the table like:

exec dbo.TruncTable

Answer 4

Don't GRANT, hide...

CREATE TRIGGER TRG_MyTable_Foo 
WITH EXECUTE AS OWNER
INSTEAD OF DELETE
AS
IF CONTEXT_INFO() = 0x9999
BEGIN
    TRUNCATE TABLE MyTable
    SET CONTEXT_INFO 0x00
END
GO

SET CONTEXT_INFO 0x9999
DELETE MyTable WHERE 1=0

SET CONTEXT_INFO may be is without any doubt better to separate a normal DELETE from a TRUNCATE TABLE

I haven't tried this...

Edit: changed to use SET CONTEXT_INFO.

Answer 5

You can create a stored procedure with execute as owner to only one table or a store procedure to any table:

CREATE PROCEDURE [dbo].[spTruncate]
    @nameTable varchar(60)  
    WITH EXECUTE AS OWNER
    AS

SET NOCOUNT OFF;
DECLARE @QUERY NVARCHAR(200);

SET @QUERY = N'TRUNCATE TABLE ' + @nameTable + ';'

EXECUTE sp_executesql @QUERY;