Path: dp-news.maxwell.syr.edu!spool.maxwell.syr.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!postnews.google.com!j33g2000cwa.googlegroups.com!not-for-mail From: jkundu@yahoo.com Newsgroups: comp.databases.oracle.server Subject: Re: Oracles streams stability for 9.2.0.5 Date: 5 May 2006 06:52:51 -0700 Organization: http://groups.google.com Lines: 17 Message-ID: <1146837171.834175.254170@j33g2000cwa.googlegroups.com> References: <1146151071.224224.109160@e56g2000cwe.googlegroups.com> <1146153299.960399.278010@e56g2000cwe.googlegroups.com> <1146154502.043932.51490@e56g2000cwe.googlegroups.com> NNTP-Posting-Host: 24.62.74.65 Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" X-Trace: posting.google.com 1146837178 12524 127.0.0.1 (5 May 2006 13:52:58 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Fri, 5 May 2006 13:52:58 +0000 (UTC) User-Agent: G2/0.2 X-HTTP-UserAgent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0; .NET CLR 2.0.50727),gzip(gfe),gzip(gfe) Complaints-To: groups-abuse@google.com Injection-Info: j33g2000cwa.googlegroups.com; posting-host=24.62.74.65; posting-account=hQY7Dw0AAADXodn4eJa47wR5ejoXIJji Xref: dp-news.maxwell.syr.edu comp.databases.oracle.server:266954 I am not sure why you think logging the supplemental information into the undo results in a double penalty. Every block change in Oracle creates a before image (undo), and an after-image (redo). Supplemental information always pertain to the before-image (since the columns are not going to change), and is only logged in the before-image part (undo). Having said that, supplemental logging does add an overhead, especially for tables that do not have any unique/primary constraints defined. Note if constraint maintenance overhead is the reason that you do not want to define such a constraint, you can always define RELY constraints to direct the supplemental logging mechanism to log a subset of columns that uniquely identify the row, although there is no unique/primary constraints being maintained on the table. Regards -Joydip