RE: Rebuilding indexes

  Hello, Terry,

  unrecoverable_change# is SCN of the last unrecoverable operation (NOLOGGING)
  unrecoverable_time - timestamp of the last unrecoverable operation They are kept on "per file" basis.

   If you have unrecoverable_time several months ago, most likely, before you've taken datafiles for your standby, you most likely dont have any recoverability problem.
Only situation, when unrecoverable_change# on stanby DB is less than unrecoverable_change# on primary is an issue, and can be recovered only by taking fresh hot backup of the corresponding datafile from primary database.

   If you have distinct unrecoverable_change# on stanby and primary, standby database if definitely missing some DML, although it can be opened and tablespaces will be accessable. You will get error later, when trying to access some data segment, modified with NOLOGGING on primary. I think, this indicator is reliable.

   To check data quality on standby I'd suggest not only open database and check all tablespaces available, but doing full export to /dev/null and check UNUSABLE indexes. Just in case...

   Can somebody correct me, if I'm wrong...

   Vadim Gorbounov
   Oracle DBA

-----Original Message-----
Sent: Friday, June 01, 2001 3:37 PM
To: Multiple recipients of list ORACLE-L

Jeremiah Wilton wrote:

>
> Vadim Gorbounov mentioned the column 'unrecoverable_change#' in
v$datafile.
> This looks like an SCN, not a count of unrecoverable changes. Either way,
it
> seems like a useful way to decide if a datafile shoule be refreshed onto
the
> standby. I can even imagine improving a standby log applier that could be
made
> to refresh such files from the primary automatically.

I'm not sure this is an accurate indicator. There is also a column 'unrecoverable_time' in v$datafile. I checked a database that we have a standby
for. It had files that had a non-zero value for unrecoverable_change# and the
unrecoverable_time (in both production and standby) was several months ago. The
database has been bounced several times between the unrecoverable_time and today.
The db has been tested for recoverability (since we just recently made a standby of
it); and the standby opens OK and the tablespaces are accessable.

I thought at first that it was because these were locally managed tablespaces, but
at least one is dictionary managed. What else should/could I look for? Since this
is a new process for us, it would be nice to have something to know to look for to
trigger a refresh of the standby or files on the standby.

>
> On another topic, I believe I qualify for some sort of award as uber geek.
> This week I obtained the Washington State license plate "ORA DBA" for my
'74
> Volvo.
>
> It got me thinking that it would be fun to have some bumper stickers made
up for
> members of this list. Some ideas I had:
>
> "ARE YOU AN IDIOT?"
>
> or
>
> "SHUTDOWN ABORT"
>

Or "HELP I'M AN IDIOT.

>
> --
> Jeremiah Wilton
> http://www.speakeasy.net/~jwilton

Terry

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