RE: Question on NEXT_CHANGE#
- From: Jonathan Lewis <jonathan@xxxxxxxxxxxxxxxxxx>
- To: Nassyam Basha <nassyambasha@xxxxxxxxx>
- Date: Mon, 30 Dec 2013 11:44:47 +0000
I did a couple of log file dumps as well (1.2.0.4), just to confirm that there
was a fairly regular gap between the last SCN recorded for a redo change record
in the file and next_change# recorded in the file header - and it is a
persistent phenomenon.
As PS Thomas pointed out, the sequence of SCNs recorded in the redo log does
show gaps (and I've often occasionally why an SCN sometimes jumps by 2 when
I've been expecting an increase of 1 - though I've never looked very closely).
One thought that may be worth pursuing is that various actions have to update
the control file - taking out CF enqueues while they do so - I don't think you
see redo records for such changes, but perhaps the SCN is still incremented
because of thses changes. If so the little gap in SCNs at the end of log file
may simply reflect the changes made to the control file as Oracle updates the
records relating to the old and new log files.
(A simple test - does the size of the gap change with the number of log files
per log file group ?)
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
@jloracle
________________________________
From: Nassyam Basha [nassyambasha@xxxxxxxxx]
Sent: 30 December 2013 06:12
To: Jonathan Lewis
Cc: ORACLE-L
Subject: Re: Question on NEXT_CHANGE#
Hi Jonathan,
Thanks for the reply. I used dump method over archive log sequence 31 and it
has last SCN as 2432672 where am expecting 2432676. From the last redo record
the hex value "0x0000.00251ea0" i have converted to decimal and the last value
is indeed 2432672. From this method also we can't see any system change
records?
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