Re: what exactly does 'cosistent read' mean?

Hi Xho,

Thanks for your mail. I have discussed the matter with a tech.support engineer from oracle , he told me that even there was no dml , the dbserver could do consistent read . This is possible when there exists long running queries which use same tables . In order to protect consistency , multiple version of the same blocks are created in cache.

These are what the tech.support has returned to me , but this time i am still confused .I have checked the 'cr' counts in buffer cache , the number is insignificant but i have huge number of consistent gets.

Still loking for an explanation....

Kind Regards,
hope

ctcgag_at_hotmail.com wrote in message news:<20040614133519.714$Bi_at_newsreader.com>...
> hopehope_123_at_yahoo.com (utkanbir) wrote:
> >
> > My question about this 'consistent_gets' . What i know is
> > consistent_get is used for multi-versioning . My system is a
> > datawarehouse and i have no updates during a day , but i see lots of
> > consistent gets in v$sess_io , may be my understanding about cr is
> > wrong.
>
> The session is in the dark when it issues the CR request. Whether the
> block actually needs any undo applied to it is determined as part of the CR
> request itself, not before the request is issued. So as long as the
> session *might* in principle need the block to be cleaned up, it issues a
> CR.
>
> Or at least that is my understanding.
>
> Xho
Received on Wed Jun 16 2004 - 02:37:45 CDT