SQL SERVER – Difference Between ROLLBACK IMMEDIATE and WITH NO_WAIT during ALTER DATABASE

Today, we are going to discuss about something very simple, but quite commonly confused two options of ALTER DATABASE.

The first one is ALTER DATABASE …ROLLBACK IMMEDIATE and the second one is WITH NO_WAIT.

Many people think they are the same or are not sure of the difference between these two options. Before we continue our explaination, let us go through the explanation given by Book On Line.

ROLLBACK AFTER integer [SECONDS] | ROLLBACK IMMEDIATE

Specifies whether to roll back after a specified number of seconds or immediately.

NO_WAIT

Specifies that if the requested database state or option change cannot complete immediately without waiting for transactions to commit or roll back on their own, then the request will fail.

If you have understood the difference by now, there is no need to proceed further. If you are still confused, continue with the rest of the post.

There is one big difference between ROLLBACK and NO_WAIT. In case incomplete Transaction ALTER DATABASE … ROLLBACK rollbacks those incomplete transaction immediately, where as ALTER DATABASE … NO_WAIT will terminate and rollback the transaction of ALTER DATABASE … NO_WAIT itself.

I think it can be clearly explained with the help of the following images.

Option 1: ALTER DATABASE … ROLLBACK

Connection 1 – Simulating some operation using WAITFOR DELAY
WAITFOR DELAY '1:00:00'

Connection 2
ALTER DATABASE TestDb
SET SINGLE_USER WITH ROLLBACK IMMEDIATE;

Option 2: ALTER DATABASE … NO_WAIT

Connection 1 – Simulating some operation using WAITFOR DELAY
WAITFOR DELAY '1:00:00'

Connection 2
ALTER DATABASE TestDb
SET SINGLE_USER WITH NO_WAIT;

Let me know if this example was simple enough.

Reference : Pinal Dave (http://blog.SQLAuthority.com)

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19 thoughts on “SQL SERVER – Difference Between ROLLBACK IMMEDIATE and WITH NO_WAIT during ALTER DATABASE

  1. Hi Pinal,
    Just to get this clear, in case of the NO_WAIT option, if there are incomple transactions in the database, then the NO_WAIT will error out?

    Thank you

  2. Nice to be back here commenting

    so Pinal, what’s your recommendation method?

    I almost always use WITH ROLLBACK IMMEDIATE since I don’t want to wait for others :)

    NO WAIT makes me wait on others by failing ;)

    • Hello Jerry,

      Welcome back.

      I usually give some time for trans to rollback. So I usually use with rollback with sometime delay of 30 seconds.

      Kind Regards,
      Pinal

  3. Books online says –

    NO_WAIT

    Specifies that if the requested database state or option change cannot complete immediately without waiting for transactions to commit or roll back on their own, the request will fail.

    Pinal did you mean to say this ?

    1. If you dont specify any option – Alter database will wait for transactions to complete and then execute

    2. If you specify rollback- alter database, will rollback all transaction immediately and then effect the alter database changes

    3. If you specify NO_WAIT, dont wait for transaction to complete, try executing my alter db statement, and let the alter fail for its specified exception. This wouldnt have been the case for the 1. one. it would have waited for the transact to complete and then the alter could succeed or fail based on the context of alter.

    • Hello Vinod Sir,

      This is great observation and I am fortunate that you are here to help me clear this doubt further.

      Yes, 1 and 3 are same but in case of the 1st, it will wait for the transactions to complete. Many time, it waits for long time and times out. In case of 3, if Alter is not executed right away, it fails immediately.

      Kind Regards,
      Pinal

      • hi pinaldave sir,
        At wich situation we use this statements
        ROLLBACK IMMEDIATE and WITH NO_WAIT during ALTER DATABASE
        mY mailid [email removed]
        am waiting for ur reply
        Thanks and regards
        Ramakrishna

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  5. Pinaldave,

    Thank you for the article. Where in the interface can I see the current settings for each database?

    Thank you,
    Jim Christmas

  6. Hi, I got this scenario…
    I call an SP that loop through a service table for create a dinamic SQL for ALTER VIEW, FROM table “A_Products” to “B_Products”…etc…

    I try to do this operation with less rumors underlayer for not create deadlock victims…

    Lately when try to do #2 ALTER my SP catch errors and my production DB (DB1) remains in single user mode.

    Is there another way for optimize this switch from “tables A” to “tables B”?
    Many times all is gone but when something wrong is a problem ’cause my production DB1 remais in SINGLE USER MODE.

    Thanks for advises
    —————————–.

    ALTER DATABASE DB1 SET SINGLE_USER WITH ROLLBACK IMMEDIATE

    –Sometis here i got error deadlock victims and DB1 remains in SINGLE_USER MODE
    ALTER DATABASE DB2 SET SINGLE_USER WITH ROLLBACK IMMEDIATE

    BEGIN TRANSACTION @MyTran;

    WHILE @MIO_ID >0
    BEGIN
    SELECT @table_name_to = TABLE_NAME_TO
    FROM DB1.dbo.service_import02
    WHERE MIO_ID = @MIO_ID

    EXEC(‘ALTER VIEW ‘+ @ActualSchemaIs + ‘.’+@Prefix_View + @table_name_to + ‘ AS
    SELECT *
    FROM ‘+ @DB_name + ‘.’ + @ActualSchemaIs + ‘.’ + @Prefix_New + @table_name_to
    )

    SET @MIO_ID = @MIO_ID-1
    END — WHILE @MIO_ID >0

    IF @@error = 0
    BEGIN
    COMMIT TRANSACTION @MyTran;

    ALTER DATABASE DB1 SET MULTI_USER

    ALTER DATABASE DB2 SET MULTI_USER

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  8. I tested on my computer, and found both of the codes will not generate error. The error you received is that you have set the DB to single_user, you tried to set it as single_user again.

  9. i’m wrong, you are right

    While we are using ALTER DATABASE, we can use any of the options “ROLLBACK IMMEDIATE” or “WITH NO_WAIT”.

    When we use “ROLLBACK IMMEDIATE”, it rollbacks other transactions which are running currently in database and successfully execute “ALTER DATABASE” command.

    When we use “WITH NO_WAIT”, it kills the “ALTER Database” transaction itself, if any other transactions are running currently in database.

    We can specify time (in seconds) also for Rollback, “ROLLBACK AFTER 100″. This will wait until 100 seconds to complete other transactions. After 100 seconds, it kills the other transactions and successfully executes “ALTER DATABASE” command.

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