doubt regarding undo data

[Former Member]

Hi Team,

I have a doubt , how does HANA handle undo data compared oracle , db6. Oracle like we have the undo tablespaces.

Here is there no requirement to have undo ?

Message was edited by: Tom Flanagan

[lbreddemann · Accepted solution]

Hey there 3CPO (or what was the name again? )

As SAP HANA comes with two storage engines for table data, there exist two different ways to keep information required for an UNDO.

For the row store tables, the old data is internally saved in virtual UNDO files and removed after the transaction that created it finished.

For column store tables all data changes are happening in the delta store anyhow. As the delta store is an append-only data structure the old version of records (that's what is required for the UNDO) are present in the main, the delta or in both stores. To perform the UNDO all that's required is to mark those records as 'current' again.

- Lars

[Former Member · Accepted solution]

Lars,

Guten Tag!

You already know me , i thought you and richard are busy with the new book.

Most eagerly awaited book.

Thanks for the info. So its pretty much like maxdb for the row store part.

User id was from the old scn so was using the same.

[lbreddemann · Accepted solution]

Well, the book is currently in the press - so we're busy with other stuff again...

- Lars

[Former Member]

Krishna,

Its worth enough to respond to your post.

If you would have worked on SAP then you would have known what i meant by SAP on hana.

Let me explain for the benefit of other users, i meant was business suite or BW or any other netweaver application.

My query was that how does hana handle undo , provided we are running sap applications on hana.

Responses from you were related to sql editor , now tell me if this is related.

[Former Member]

Hello P517710,

Here is there no requirement to have undo ? ( )

Anyways, If you collectively want to undo the records containing the actions of transactions, then you will have to set the "AUTO COMMIT" flag of the Sql Editor to false.

=> use a simple command called " ROLLBACK; "

Regards,

Krishna

[Former Member]

so the undo is implemented at the application level and database execution will happen on that.

If a job is running and i want to cancel it , so it has to undo the whole stuff. How does HANA handle it?

[Former Member]

Krishna,

My question was not related to sql editor , i was asking from a whole application perspective.

[Former Member]

Looking at the previous question that you have posted i am assuming that you are facing an issue while resetting a node in hana repository.

Check this out:

http://scn.sap.com/thread/3373968

Cheers,

Krishna

[Former Member]

Thats not what i was looking out for.

this is not a standalone hana. We are running SAP application on hana.

I presume you are not from SAP background. I was trying to ask about SAP on hana.