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January 2013

Oracle 11gR2 RAC Installation on Oracle Linux 6

I spent today updating my Oracle 11gR2 RAC installation on OL6 article. The original article used an older version of VirtualBox , which meant some of the screen shots looked a little dated. It’s now updated to VirtualBox 4.2.6, so it should be a little less confusing for anyone who is new to VirtualBox.

I’ll probably update the OL5 RAC article some time this next week, since that article uses VirtualBox 3.2.8, which is pretty much ancient history now. :)

Cheers

Tim…

Quiz Night

Warning – this is a catch question, and I haven’t given you enough information to have any idea of the right answer; though, by telling you that I haven’t given you enough information to have any idea of the right answer, you now have some information that might help you to get closer to the right answer.

I have a simple heap table with no indexes. Immediately after flushing the buffer_cache I’ve run a query that looks ike this:

select max(column_ZZZ) from table_X;

The most significant session stats for this operation are as follows:

Over-indexing

This is the text of an article I published in the UKOUG magazine a few years ago, but it caught my eye while I was browsing through my knowledge base recently, and it’s still relevant. I haven’t altered the original apart from adding a couple of very brief comments in brackets [Ed: like this].

Over-indexing

One of the strengths of a relational database is that you should be able to throw any reasonable query (and even some unreasonable queries) at it and it will be able to return the right answer without being told how to navigate through the data.

There’s no guarantee, though, that you’ll get the answer quickly unless you’ve given the database some help by turning your logical model into a sensible physical implementation. Part of the physical implementation will be the choice of indexes – and this article reviews one of the commonest indexing issues that I see in OLTP systems

Displaying ASM Partner Disks

Here is a quick SQL which I sometimes use to show people disks and their respective partners (grouped by a failure group) inside an ASM disk group every time I need to explain both of these concepts.

An example output from a quarter rack Exadata with a normal redundancy disk group:

SQL> column p format a80
SQL> variable group_number number
SQL> exec :group_number := 1;

PL/SQL procedure successfully completed.

SQL> select d||' => '||listagg(p, ',') within group (order by p) p
from (
select ad1.failgroup||'('||to_char(ad1.disk_number, 'fm000')||')' d,
ad2.failgroup||'('||listagg(to_char(p.number_kfdpartner, 'fm000'), ',') within group (order by ad1.disk_number)||')' p
from v$asm_disk ad1, x$kfdpartner p, v$asm_disk ad2
where ad1.disk_number = p.disk
and p.number_kfdpartner=ad2.disk_number
and ad1.group_number = p.grp
and ad2.group_number = p.grp
and p.grp = :group_number

Set Up Exadata for Cloud Control 12.1.0.2

I recently helped set up an Exadata X2-8 Database Machine with the latest version of OEM Cloud Countrol (12.1.0.2). A few documents do exist for this process – the most useful of which are the Exadata Discovery Cookbook and the Setup Automation Kit. However, I found a few inconsistencies and problems; I think the existing documents I found were written on older versions of OEM and older versions of the tools. Also, there are some additional steps for older Exadatas which didn’t apply to my case.

Set Up Exadata for Cloud Control 12.1.0.2

I recently helped setup an Exadata X2-8 Database Machine with the latest version of OEM Cloud Countrol (12.1.0.2). A few documents do exist for this process – the most useful of which are the Exadata Discovery Cookbook and the Setup Automation Kit. However I found a few inconsistencies and problems; I think the existing documents I found were written on older versions of OEM and older versions of the tools. Also there are some additional steps for older Exadatas which didn’t apply to my case.

Set Up Exadata for Cloud Control 12.1.0.2

I recently helped setup an Exadata X2-8 Database Machine with the latest version of OEM Cloud Countrol (12.1.0.2). A few documents do exist for this process – the most useful of which are the Exadata Discovery Cookbook and the Setup Automation Kit. However I found a few inconsistencies and problems; I think the existing documents I found were written on older versions of OEM and older versions of the tools. Also there are some additional steps for older Exadatas which didn’t apply to my case.

RHCE Certification Articles…

Just before I started my current job I was planning on doing the RHCSA and RHCE exams for a bit of fun. In preparation for that I started to write the revision notes for each of the exam objectives. I got to the end of the RHCSA exam objectives, then my plan kind-of stalled, what with starting the new job etc.

Over the Christmas holiday I got some time to start the notes for the RHCE exam. If anything, the syllabus for this exam is a little simpler as many of the sections follow the same basic format. This full list of RHCE exam objectives includes the links to all the articles I’ve written to cover the objectives. There are still 5 to complete, but hopefully I’ll get those done soon.

The new articles I wrote include:

Analysing Statspack 13

A recent (Jan 2013) post on the OTN database forum reported a performance problem on Oracle 9.2.0.6 (so no AWR), and posted a complete statspack report to one of the public file-sharing sites. It’s been some time since I did a quick run through the highlights of trouble-shooting with statspack, so I’ve picked out a few points from this one to comment on.

As usual, although this specific report is Statspack, the same analysis would have gone into looking at a more modern AWR report, although I will make a couple of comments at the end about the extra material that would have been available by default with the AWR report that would have helped us help the OP.

Philosophy 20

It’s important to revisit the questions you think you’ve answered from time to time. You may find that your previous answer was wrong or incomplete; you may find that looking at your past answers may give you ideas for new questions.