To: oracle-l@freelists.org
From: Dave Morgan <oracle@1001111.com>
Subject: Database Incarnations
Message-ID: <9f93a585-0d4f-c87b-d215-aa6477b5b1ba@1001111.com>
Date: Tue, 2 Feb 2021 11:26:23 -0700
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Hello All,
     I have a question about where the database stores Incarnation data. 
The background: As a hot backup my client uses
archive log shipping and application to a database that is not open, but 
is mounted. On Windows using 11.2.0.3

During a series of hardware failures we failed over, were still impacted 
by the underlying issue and so re-opened the original
copy. Since this is in 11.2.0.3 the failure required an open database 
resetlogs despite full recovery being performed (known bug)

Once life is good again I have to rebuild the hot standby. I do this by 
blowing it away completely (datafiles, redo, control files) and
perform a controlfile restore and then a database restore. At this time 
when  I try to apply archivelog files it says "Sorry
your system file 0001 is from an orphan incarnation". Sure enough the 
hot standby is +1 ahead of production. The fix is trivial but
how does the database know this? The manual says V$DATABASE displays 
information from the control file but the control file is
from production which knows nothing about the extra open and incarnation 
on the hot backup.

|RECOVERY_TARGET_INCARNATION# |Incarnation number where all data files 
are recovered by the |RECOVER DATABASE| command
|LAST_OPEN_INCARNATION#| Record number of the incarnation in 
|V$DATABASE_INCARNATION| that was last opened successfully --

I can find no information on where v$database_incarnation gets its data 
and the only table with INCARNATION in its name is
RECENT_RESOURCE_INCARNATIONS$ which has NULL for TABLESPACE_NAME in 
DBA_TABLES.

If it's not in any tablespace, and not in the controlfile where is it 
stored?

Any ideas or even better knowledge?

TIA
Dave

Dave Morgan
Senior Consultant, 1001111 Alberta Limited
dave.morgan@1001111.com
403 399 2442


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    Hello All,<br>
        I have a question about where the database stores Incarnation
    data. The background: As a hot backup my client uses<br>
    archive log shipping and application to a database that is not open,
    but is mounted. On Windows using 11.2.0.3 <br>
    <br>
    During a series of hardware failures we failed over, were still
    impacted by the underlying issue and so re-opened the original<br>
    copy. Since this is in 11.2.0.3 the failure required an open
    database resetlogs despite full recovery being performed (known bug)<br>
    <br>
    Once life is good again I have to rebuild the hot standby. I do this
    by blowing it away completely (datafiles, redo, control files) and<br>
    perform a controlfile restore and then a database restore. At this
    time when  I try to apply archivelog files it says "Sorry<br>
    your system file 0001 is from an orphan incarnation". Sure enough
    the hot standby is +1 ahead of production. The fix is trivial but<br>
    how does the database know this? The manual says V$DATABASE displays
    information from the control file but the control file is <br>
    from production which knows nothing about the extra open and
    incarnation on the hot backup.<br>
    <br>
    <code class="codeph">RECOVERY_TARGET_INCARNATION#    </code>Incarnation
    number where all data files are recovered by the <code
      class="codeph">RECOVER DATABASE</code> command <br>
    <code class="codeph">LAST_OPEN_INCARNATION#</code>                
    Record number of the incarnation in <code class="codeph">V$DATABASE_INCARNATION</code>
    that was last opened successfully --<br>
    <br>
    I can find no information on where v$database_incarnation gets its
    data and the only table with INCARNATION in its name is<br>
    RECENT_RESOURCE_INCARNATIONS$ which has NULL for TABLESPACE_NAME in
    DBA_TABLES.<br>
    <br>
    If it's not in any tablespace, and not in the controlfile where is
    it stored?<br>
    <br>
    Any ideas or even better knowledge?<br>
    <br>
    TIA<br>
    Dave<br>
    <br>
    <pre class="moz-signature" cols="72">Dave Morgan
Senior Consultant, 1001111 Alberta Limited
<a class="moz-txt-link-abbreviated" href="mailto:dave.morgan@1001111.com">dave.morgan@1001111.com</a>
403 399 2442
</pre>
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