Search

Top 60 Oracle Blogs

Recent comments

January 2013

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.

Blog advert

Just a quick note to say that I found a blog over the weekend with a number of interesting posts, so I thought I’d pass it on: http://www.bobbydurrettdba.com/

There’s a really cute example (complete with test case) of an optimizer bug (possibly only in 11.1)  in the December archive: http://www.bobbydurrettdba.com/2012/12/04/index-causes-poor-performance-in-query-that-doesnt-use-it/

Oracle and the cloud. A brief history…

This morning I read this post about Oracle Cloud from Tuula Fai.

What really annoys me about this post is I was at Oracle OpenWorld (about 3 years ago) when Larry was on stage telling us that Cloud was a meaningless fad. Fast forward to OOW 2012 and it would be easy to believe that Oracle invented the cloud, as I mentioned here. At OOW 2012 he openly stated Oracle started to write Fusion Apps for the cloud 7 years ago. Dude! That is not true. You initiated a program to rewrite Fusion Apps to be a browser-based replacement for EBS, which then happily coincided with the whole cloud thing at a later date. At least this post acknowledges that could have been an accident…

Oracle 11.2 and the direct path read event

In my previous post I touched the topic of a “new” codepath (codepath means “way of utilising the operating system”) for of full segment scans. Full segment scan means scanning a segment (I use “segment” because it could be a partition of a table or index) which is visible commonly visible in an explain plan (but not restricted to) as the rowsources “TABLE ACCESS FULL”, “FAST FULL INDEX SCAN” and “BITMAP FULL SCAN”.

Look at my presentation About multiblock reads to see how and when direct path reads kick in, and what the difference between the two is. Most notably, Oracle has released very little information about asynchronous direct path reads.

Nexus 4 : Broken Back Panel (Final Update)…

Today I received a case for my Nexus 4. I got this case for £2.90 from Amazon along with free delivery. It came with a screen protector and polish cloth. :)

I put some sellotape over the shattered glass on the back, but couldn’t be bothered to tape over all the radiating cracks, since they are not shedding glass shards. I put the phone into the case and I’m now going to try my best to forget that LG (and Google by association) are a bunch of asses over the design of the back panel of this phone.

From a functional perspective, it’s hard to tell the phone apart from the Nexus 7 tablet, so I have no gripes in that respect. My rantings have purely been about the terrible choice of materials for the back panel.

Demystifying ASM REQUIRED_MIRROR_FREE_MB and USABLE_FILE_MB

A recurring question in my classes is how Oracle Automatic Storage Management (ASM) calculates the REQUIRED_MIRROR_FREE_MB and USABLE_FILE_MB disk group values. As usual the answer is: It depends! ;-) In short: the REQUIRED_MIRROR_FREE_MB value in V$ASM_DISKGROUP indicates how much free space is required in an ASM disk group to restore redundancy after the failure of […]

Oracle Linux support in ESXi

For quite some time now I am using ESXi 5 update 1 for my lab server and I’m very happy with it. In my lab environment I am not too picky what to run and do not worry about support too much. It’s not production!

One area of concern has been the support for Oracle’s own kernel: UEK or Unbreakable Enterprise Kernel. UEK comes in two editions, one based on 2.6.32, just like Red Hat’s kernel for Red Hat 6. The difference is that you can get UEK/1 (2.6.32.xxx) for Oracle Linux 5.x as well instead of 2.6.18xxx which is otherwise the default.

Oracle’s second iteration of kernel UEK is unsurprisingly named UEK2 and it’s initially based on 3.x but keeps the name to 2.6.39.x for compatibility reasons. UEK2 has some really nice features taken from the Upstream kernel and it is also supported for the Oracle database.