Re: posting to informix newsgroup instead of oracle!

utkanbir wrote: > Hi Informix Gurus, > I posted a simple question to oracle newsgroup but that place is very silent. > May be you can help me . Here is my question about oracle: That sounds like people who say, "You're in computers, aren't you! Can you fix my PC?"! > i am new with oracle. Me too. > I am sorry if the question is very simple. I'm sure it is for the Oracle list, but it's a lot harder here on the Informix list. > The mechanism uses a rollback segment (or > undo) concept , which stores before-images , and redo log concept > which stores transaction information. Am i right? I'm sure you are... > Guessing that i am right, Okay. > 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? You know, we ask that question ALL the time here on the INFORMIX list. :-) We use logical & physical logs in Informix for that sort of stuff. Do you think Oracle works the same as Informix? I'm going to guess here, but I'd say the free page you decided to use for the new row. Am I right? Guessing that I don't have a clue. Cheers, -- Mark. +----------------------------------------------------------+-----------+ | Mark D. Stock mailto:mdstock@MydasSolutions.com |//////// /| | Mydas Solutions Ltd http://MydasSolutions.com |///// / //| | +-----------------------------------+//// / ///| | |We value your comments, which have |/// / ////| | |been recorded and automatically |// / /////| | |emailed back to us for our records.|/ ////////| +----------------------+-----------------------------------+-----------+ sending to informix-list sending to informix-list

Mark D. Stock wrote: >utkanbir wrote: > > > >>Hi Informix Gurus, >>I posted a simple question to oracle newsgroup but that place is very silent. >>May be you can help me . Here is my question about oracle: >> >> > >That sounds like people who say, "You're in computers, aren't you! Can you >fix my PC?"! > > > >>i am new with oracle. >> >> > >Me too. > > > >>I am sorry if the question is very simple. >> >> > >I'm sure it is for the Oracle list, but it's a lot harder here on the >Informix list. > > > >>The mechanism uses a rollback segment (or >>undo) concept , which stores before-images , and redo log concept >>which stores transaction information. Am i right? >> >> > >I'm sure you are... > > > >>Guessing that i am right, >> >> > >Okay. > > > >>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? >> >> > >You know, we ask that question ALL the time here on the INFORMIX list. :-) > >We use logical & physical logs in Informix for that sort of stuff. Do you >think Oracle works the same as Informix? > >I'm going to guess here, but I'd say the free page you decided to use for >the new row. Am I right? Guessing that I don't have a clue. > >Cheers, > > All databases use rollback (or in Oracle undo) for insert statements. There are no exceptions. If they didn't the transaction couldn't be rolled back if it failed. The information as to what needs to be rolled back must be stored somewhere. Physical logs in Informix are analogous to Rollback or UNDO in Oracle. Logical logs in Informix are equivalent to log files in Oracle though the way they are used and the underlying architecture are different. You can have a non-logging transaction ... but you can not avoid rollback. And based on Oracle's MVCC architecture you'd be crazy to try. -- Daniel Morgan http://www.outreach.washington.edu/ext/certificates/oad/oad_crs.asp http://www.outreach.washington.edu/ext/certificates/aoa/aoa_crs.asp damorgan@x.washington.edu (replace 'x' with a 'u' to reply)