Re: why does an insert procude rollback segment data?

On 29 Sep 2003 07:27:09 -0700, hopehope_123_at_yahoo.com (utkanbir) wrote:

>Hi Gurus,
>As the subject explains , i am new with oracle. I am sorry if the
>question is very simple. The mechanism uses a rollback segment (or
>undo) concept , which stores before-images , and redo log concept
>which stores transaction information. Am i right? Guessing that i am
>right , my question comes: Does an insert statement needs rollback
>segment? I dont think so because insert statement does not change a
>block , but creates a new one so there is no before image record. If
>so , what is the before image of an insert statement?
>
>Kind Regards,
>hope

An insert statement does need a rollback segment, because insert statement DO change existing block. The space management of Oracle check whether a block is a candidate for insert, and ONLY will create a new block, when there are no suitable blocks available. Apart from that, you always would need a before image, because otherwise you simply can't roll back to the state your table was in, prior to your insert.

Sybrand Bakker, Senior Oracle DBA

To reply remove -verwijderdit from my e-mail address Received on Mon Sep 29 2003 - 11:30:46 CDT