Re: How much amount of Redo Generated?

On 26 Aug 2004 22:22:57 -0700, juma_gandhi_at_yahoo.com (Jumma) wrote:

>Hi,
>
>I wanted to find out the amount of transaction which is currently
>going on.
>In this regard I heard that the CPODR_BNO column of SYS.X$KCCCP table
>finds out the redo amount generated for the current redo log file.
>
> Via searching this google site, I found the solution of this.
>
>An expert said that:
> The column labelled CPODR_BNO shows the Current
>position of the Database Redo Block Number.
>Multiply by (usually) 512 bytes to get the position in more meaningful
>terms. For example, if it displays 500, it means 256KB of redo has
>been written into the current log. The number resets at each log
>switch.
>
> I like to ask why we multiply the value of CPODR_BNO with 512 in
>order to get the redo amount.
>Is that process gives the correct amount of redo generated for the
>current transactions?
>
>Is that necessary to perform logswitch manually to findout the redo
>amount as discussed above?
>
>Thanks in Advance.
>
>Juma

I'm not sure why you are so much obsessed by the amount of redo of the current transaction, and i'm not sure why you are so much obsessed by getting it from x$ views.
logminer would get you the exact information, after the transaction has been completed of course. But also you could monitor v$rollstat to see what is going.
Also, unless you are short on disk, the amount of redo is unimportant. You also shouldn't need to find out the amount of redo to decide whether your application has been designed properly (obviously it isn't)
As to your question, on almost all implementations of Oracle the redolog file is written in chunks of 512 bytes (which is documented), so I don't see why you wouldn't trust the formula.

--
Sybrand Bakker, Senior Oracle DBA