Today, we are going to discuss something very simple, but quite commonly confused two options of ALTER DATABASE. Difference Between ROLLBACK IMMEDIATE and WITH NO_WAIT during ALTER DATABASE.
The first one is the 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 explanation, 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 DB … ROLLBACK rollbacks those incomplete transactions immediately, whereas ALTER DB … NO_WAIT will terminate and rollback the transaction of 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. I would love to get your feedback in the comments area about this subject. Here are a few additional blog posts you can read on this topic:
- SQL SERVER – Delay Function – WAITFOR clause – Delay Execution of Commands
- SQL SERVER – Database Testing and Waitfor Delay – Notes from the Field #099
- SQL SERVER – Find Statistics Update Date – Update Statistics
- SQL SERVER – Delay Command in SQL Server – SQL in Sixty Seconds #055
Reference: Pinal Dave (https://blog.sqlauthority.com)
19 Comments. Leave new
It looks like those images should be switched.
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
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 ;)
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.
Pinaldave,
Thank you for the article. Where in the interface can I see the current settings for each database?
Thank you,
Jim Christmas
how to use rollback in sql server 2005 if i have delete all record from table how to retrieve all value again in a same table
Hi pinal,
where it is used in the rollback statement and what is usage of this statement..
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
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.
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.
Dear Sir,
Can u explain what and all the Process are there in “ALTER DATABASE” Command?
Hi,
I understand it this way:
with ROLLBACK Immediate –> cancels all current transactions and enforces the Alter Database statement
with NO_Wait –> cancels the Alter Database Statement itself and allows the transactions to occur and take their time.
So the funny part is the name “No_Wait”, as actually it gives the current transactions all the time they need.
So there is a mental switch here, which initially is hard to follow. Rollback Immediate cancels outstanding transactions where No_wait refers to the alter db statement and tells it: should there be outstanding transactions, forget this alter db statement – just leave it immediately, don’t bother.
So the bottom line is: they cannot be used both at the same time, right?
At least I couldn’t. Only one will work at a time.
Sometimes there are funny twists in IT and it’s quite a struggle to get these simple things straight.
Thank you
Andi
Very valid point @Andi.