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July 2016

Friday Philosophy – Tech Writing Is Like Religious Art

I’m putting together an article for Oracle Scene at the moment – I’ve delayed it for a couple of issues as we wanted the space for other tech articles, but my time has come. And I’m finding it very hard going. Why?

I’m not an expert on religious art (or religion… or art) but one thing I know is that with religious artifacts, especially things like sculpture, furniture, and plaques, they often differ from non-religious art in that the back of them is as well done as the front. I.e. if there is an ornate plaque to be created and put on the wall of a secular building, all the effort goes into the front. The back is likely to be simple or even rough. With a religious plaque, the chances are that the back will be just as well crafted as the front.

Oracle Security Expert Seminar

I am happy to announce that I will be teaching a five day Oracle Security expert seminar class with Oracle University at Oracle offices in Reading, UK from September 26th to September 30th 2016. This is a 5 days expert....[Read More]

Posted by Pete On 08/07/16 At 02:45 PM

DML and Bloom

One of the comments on my recent posting about “Why use pl/sql bulk strategies over simple SQL” pointed out that it’s not just distributed queries that can change plans dramatically when you change from a simple select to “insert into … select …”; there’s a similar problem with queries that use Bloom filters – the filter disappears when you change from the query to the DML.

This seemed a little bizarre, so I did a quick search on MoS (using the terms “insert select Bloom Filter”) to check for known bugs and then tried to run up a quick demo. Here’s a summary of the related bugs that I found through my first simple search:

Can a query on the standby update the primary ?

You would think that (with the exception of the V$ tables which are predominantly memory structures reflecting the state of various parts of the database instance) a query on a read-only standby database would have absolutely no interaction with the primary.  After all, the standby database needs to be able to run independently of the primary should that primary database be down, or destroyed.

But there’s an exception to the rule.  Consider the following example.  I create a sequence on my primary database.

Invisible Bug

At this Wednesday’s Oracle Midlands event someone asked me if Oracle would use the statistics on invisible indexes for the index sanity check. I answered that there had been a bug in the very early days of invisible indexes when the distinct_key statistic on the index could be used even though the index itself would not be considered as a candidate in the plan (and the invisible index is still used to avoid foreign key locking – even in 12c – it’s only supposed to be invisible to the optimizer).

Setting Environment Variables in Application Server/Process Scheduler Tuxedo Domains

The topic of how to manage environment variables was mentioned recently on the PeopleSoft Administrator Podcast

Recently I have built a pair of PeopleSoft environments for a proof-of-concept and have faced into exactly this problem.  I have two PS_APP_HOMEs (application homes) share the same PS_HOME (PeopleTools home).  The environment variables need to be correct before I open psadmin to administer the application server and process scheduler domains.

Create a SQL Profile to let the Optimizer ignore hints in #Oracle

Something I presented recently during an Oracle Database 12c Performance Management and Tuning class. Hints are a double-edged sword; they may do more harm than good. What if  hinted SQL comes from an application that you as the DBA in charge can’t modify? You can tell the Optimizer to ignore that nasty hint.

One method is to use alter session set “_optimizer_ignore_hints”=true; This will make the optimizer ignore all hints during that session  – also the useful ones, so maybe that is not desirable. The method I show here works on the statement level. The playground:

What’s Involved in a New STIG Release?

This blog post was prompted by a comment on my website by Chris Peterson, where he asked why the 11g STIG checklist doesn’t work against Oracle Database 12c.  This required a more comprehensive answer than I could give in a simple comment, so that’s what this blog post is all about.  Let’s start off with a bit of an introduction for those of you that are asking, “What the heck is a STIG anyway?” </p />
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Centenary

I rarely blog about anything non-technical but after the events last Friday (1st July) I wanted to say something about the pride that I shared with several hundred parents around the country as they saw the effect their offspring created through a living memorial of the terrible waste of life that happened  a hundred years ago on 1st July 1916 when some 70,000 soldiers (a very large fraction of them British) were killed or injured on the first day of the battle of the Somme.

Skinny Banners and the Corporate Laptop

Prevent the narrow display of banner images from Squarespace websites on
laptops with 1366 x 768 screens. This includes many corporate laptops, as
well as budget models from discount stores. 



Read the full post at www.gennick.com/database.