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Database Feed

Oracle Database, Oracle 10g, Oracle 11g, Oracle XE, Oracle RAC, Oracle Instant Client, Oracle Data Guard and Oracle Exadata resources, news, and support articles.

CPU-starved LGWR

In my recent post I showed how log file sync (LFS) and log file parallel write (LFPW) look for normal systems. I think it would also be interesting to compare that to the situation when LGWR does not have enough CPU.

apropos("^ore")

We have all been in the position of trying to find the name of a command in a language, particularly if you are not totally sure of the full command name. I've been working with R a lot recently and in particular Oracle R Enterprise. I was always trying to remember what the full command name was. Then I found the apropos function. The apropos function allows you to search R for commands based on a part or partial name. You can use regular expression syntax to define what part of the function name you are looking for.

Can you have high redundancy files in a normal redundancy diskgroup?

One of the perks of teaching classes is that I get to research questions asked. In the last Exadata Administration Class I taught someone asked: can you have your disk groups in Exadata on normal redundancy yet have certain databases use high redundancy? This would be a good interview question …

The answer is yes, which I remembered from researching material on the 11g RAC book but I wanted to prove that it is the case.

Documentum upgrade project - D2EventSenderMailMethod & bug with Patch 12

We started the Documentum upgrade in the wintertime and our jobs ran successfully by following the defined schedule. Once we moved to the summertime we hit an issue: A job that was scheduled for instance at 4:00 AM was executed at 4:00 AM, but also started every 2 minutes until 5:00 AM. We had this issue on all our 6.7SP2P009 repositories - on upgraded as well as on new repositories.
Before opening an SR in powerlink, I first checked the date and time with the following query.
On the content server using idql:
 

Blogging 101 and Writing 101 Are Back!

You’ve just started your shiny new blog and you’d like some help as you get up to speed on WordPress.com. Or, maybe you’d like some inspiration to write every day. On September 15th, we kick off two free Blogging U. courses: Blogging 101 and Writing 101. They might be just what you need to whip your blog into shape and/or establish your writing habit.

FIXED_DATE and LAST_ANALYZED

I tested this on Oracle 11.2.0.1. You need to be careful when looking at the LAST_ANALYZED column in USER_TABLES.

Oracle: How to move OMF datafiles in 11g and 12c

With OMF datafiles, you don't manage the datafile name. Then how do you set the destination when you want to move them to another mount point? Let's see how it is easy (and online) in 12c. And how to do it with minimal downtime in 11g.

testcase

I create a tablespace with two datafiles. It's OMF and goes into /u01

Piggyback commits

Not every commit results in a redo write. This is because there are multiple optimizations (some controlled by the user e.g. with COMMIT_LOGGING parameter, some automatic) that aim at reducing the number of redo writes caused by commits by grouping redo records together. Such group or “piggyback” commits are important for understanding log file sync waits and various statistics around it.

Index Growing Larger Than The Table

Here is a very simple demonstration of a case where an Index can grow larger than the table.  This happens because the pattern of data deleted and inserted doesn't allow deleted entries to be reused.  For every 10 rows that are inserted, 7 rows are subsequently deleted after their status is changed to "Processed".  But the space for the deleted entries from the index cannot be reused.
SQL>
SQL>REM Demo Index growth larger than table !
SQL>
SQL>drop table hkc_process_list purge;

Table dropped.
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