Oracle Observations

February 21, 2015

oracle midlands #om7

Filed under: Uncategorized — bigdaveroberts @ 4:48 pm

Unusually, frequent bloggers Tim Hall and Martin Widlake were absent from the attendees at Oracle midlands January event.

So for the benefit of the absent, a review of the 2 talks.

The first talk by eDBAs James Anthony was on the topic of the new in memory option

I had attended a couple of talks by @SQLMaria at #ukoug_tech14 on this topic so assumed that I wouldn’t get much new from this session.

I was wrong, the first half covered the theoreticals of the new functionality, which overlapped heavily with the sessions I had previously attended.

However, eDBA had been part of the beta program and James proceeded with an analysis based on real world data-sets, with real figures for the actual levels of compression achieved, which without intelligent column selection didn’t come close to the figures quoted by Oracle.

However with the intelligent selection of columns for the in memory option, the figures came incredibly close to the theoretical figures quoted by oracle.

The fact that the Syntax for selectively caching columns was obscure was observed. The fact that selective caching appears to be crucial to get the greatest benefit from this new functionality makes this complexity an anomaly.

I suspect an intelligent algorithm will be introduced in a future Oracle release to make this functionality more beneficial out of the box.

The second talk by Yves Colin was on a specific bottleneck that was observerd and resolved by paralleliasing the target database table.

This second talk was lighter on the theoretical and heavy on the practical demo aspect.

This was a good thing, because I would have not believed the observations in the talk without the demos.

In essence the question was how do we reduce a bottleneck on inserts by a combination of changes to partitioning and indexing.

The issue appeared to be caused by the fact that the date/time of the data measurement was causing hot blocks that were acting as a bottleneck.

The solution was not as expected.

I would have expected that moving the date time from being the first entry in the index would resolve the hot block problem.

However the requirement was to improve the insertion rate without compromising the performance of the reporting function.

The result was by changing the partitioning and keeping the counter intuitive index, then acceptable insert performance was achieved without compromising reporting performance.

In short, a session that explains to you that what you thought you understood was wrong is so much more useful than a session that adds details to the level of knowledge that you already know on a subject.

In essence, more complex scenarios need testing, simple rules of thumb break down very quickly outside of the most simple scenarios!

Ultimately one session that unexpectedly added to my knowledge and one session that blew a hole in what I thought I already knew.

An evening well spent.

#OM8 due Tuesday 03 March 18:00 – 21:00 at Innovation Birmingham, Faraday Wharf, Holt St, Birmingham B7 4BB
Edition based redefinition and plug able databases.

January 8, 2014

Oracle Midlands #1

Filed under: Uncategorized — bigdaveroberts @ 8:35 pm

I attended the first Oracle Midlands event last night.

Apart from the poor choice of hash tag, the inaugural event went well.

The 2 talks were by stalwarts of the SIG and conference circuit Tim Hall and Pete Finnegan and excellent as to be expected.

I have to admit, I’d attended both talks previously, Tims at a ukoug conference and Pete’s at this years uk oak table world conference.

I also have to admit, either Tim has updated the presentation since I last heard it, or I’d forgotten a lot. Pete’s talk, was much more recent in my mind, and my notes from the talk were still in my latest notepad, so I could compare!

It is apparent that Pete talks around his slides using them as an aid memoir, as while most of what he said was the same, it wasn’t in the same order as my notes. A sign perhaps as to how comfortable Pete is with his area of expertise.

I think a very high standard has been set with this first event, let’s hope we can keep this going at the same high level!

December 9, 2013

UKOUG Oracle Scene

Filed under: Uncategorized — bigdaveroberts @ 12:48 pm

I’ve only just noticed, it is now only the print edition of Oracle Scene that is a UKOUG member benefit.

The electronic edition can be accessed freely.

The latested edition has been announced on their facebook group:

Oracle Scene 51

However older (and special) editions can also be found here:
Oracle scene Issue 54
Oracle scene Issue 53
Oracle scene Issue 52
Oracle scene Issue 12c supliment
Oracle scene Issue 51
Oracle scene Issue 50
Oracle scene Issue 49
Oracle scene Issue 48
Oracle scene Issue 47
Oracle scene Issue 46
Oracle scene Issue 33 – 45

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December 7, 2013

The reveal – who laughed?

Filed under: Uncategorized — bigdaveroberts @ 1:27 pm

first against the wall

Oak table world UK 2013 collateral #otwuk13

Filed under: Uncategorized — bigdaveroberts @ 1:15 pm

I think most people understand the deal with UKOUG:

You do a presentation, you get a free pass.

UKOUG prefers new presentations on new topics that have not been presented before. Then you are expected to provide white papers and presentation slides for uploading to the website.

Oak table world ( is a slightly more informal affair, where presentations will be by Oak Table members and the topics can cover anything from spectrum games programming to the best of core oracle technical presentations.

For those that could make it and for those that couldn’t, but are still interested the following is a list of the presentations and the associated materials that I could locate on the internet.

Monday 2nd December 2013

Calculating Selectivity
09:00-10:00 Jonathan Lewis

I have been unable to locate a download of this presentation, however Johnathan’s blog states: “On Monday from 9:00 to 10:00 I’ll be presenting “Calculating Selectivity” (a shortened version of the presentation I’ll be giving at RMOUG 2014 in February)”
RMOUG have in the past made the presentation slides freely available, so we may need to wait till then for a copy of this presentation.

Hacking session: Advanced profiling of oracle using function calls
10:15-11:00 Frits Hoogland

I am presuming that this is the same presentation as the one he provided at the RMOUG 2013 conference.

Frits has conveniently posted a whitepaper here:

APEX for DBA’s
11:30-12:15 Iloon Ellen-Wolff

I am currently unable locate any handouts from Iloon associated with this session.

Her blog can be located here:

The keys to the kingdom – An Unexpected recovery tale.
12:40-13:25 Niall Litchfield

Niall has posted his presentation on prezi:

Diagnosing ASMlib
14:10-14:55 James Morle

While I have not found an associated download, the following blog post covers the same topic:

Cloudy Reality
15:25-16:10 Doug Burns

I haven’t found a copy of Doug’s presentation, but his blog can be located here:

Oracle 12c Automatic Data Optimization and Heat Map
16:35-17:35 Joel Goodman

Joel works for Oracle in various roles. Often his presentations are based on copyrighted Oracle content and usually no handouts are provided. (If you want access to the original material you can always go on the formal course!)

Joel blogs here:

Tuesday 3rd December 2013

Using Data Guard Broker
09:00-09:45 Marcin Przepiorowski

I haven’t found a copy of Marcin s presentation, but his blog can be located here:

Instant cloning and Data Agility
10:15-11:15 Kyle Hailey and Adam Leventhal

I haven’t found a copy of this presentation, but the respective blogs can be found here:
and here:

The Query Optimizer in Oracle Database 12c – What’s New?
11:30-12:30 Christian Antognini

This appears to be the same presentation form Oracle open world:

And following on from the presentation Christian has produced a bllg post where he answers a question raised during the session:

Securing PL/SQL
12:40-13:25 Pete Finnigan

Pete has provided the presentation here:

Hadoop for Oracle DBAs
14:10-14:55 Alex Gorbachev

I believe that these are the presentation slides for this session:

There is also a youtube podcast/presentation around these or similar slides:

Practical ASH
15:25-16:10 David Kurtz

While David has made the slides available here:
He actually recommends his white paper: on which the presentation was based.

Closing Keynote
16:35-17:35 Moans Nogood (mogens nørgaard)

There were no presentation slides, and I’m not sure if slides could really do justice to the presentation.

Apparently an important announcement was made by Mogens, James and Alex, but I’m sure they will be blogging about that themselves in the near future.

Too early for the big reveal!

Filed under: Uncategorized — bigdaveroberts @ 12:28 am


UKOUG Tech 13, a review (by a non attendee)

Filed under: Uncategorized — bigdaveroberts @ 12:25 am

I hadn’t expected to attend this years conference having given up my membership earlier this year, however due to unforeseen circumstances I was free on Tuesday 3rd December and resolved to pop up and catch up with friends and acquaintances.

I have to admit I was pleasantly surprised by the simplicity of the journey by road, with convenient parking close to both the convention center and my chosen hotel (The Juries Inn).

In lew of finding anyone I already knew, I adopted the first group of delegates I found that were seeking out post educational activities.

It became quickly apparent that there didn’t seem to be anything but upmarket/trendy drinking establishments within easy reach of the conference center and there were few enough of those.

It is with some fondness that I heard tales of the Tap and Spile mentioned and expressions of disappointment at the lack of a similar facility conveniently located close to the convention center.

After sampling both the local hostilities, I imposed myself on another unsuspecting group and moved on to a rather fine Indian restaurant. (‎)

I find it both strange and comforting that having split the bill ten ways an appropriate sum of £42 was required to satisfy the proprietor and providence.

In conclusion, the venue seems to be well supported with practical amenities, but slightly lacking in social ones. Possibly some further research is required of the area slightly father out, however I suspect, should the conference return to this venue, it might prove worthwhile making another appearance, however brief.

October 25, 2013

Networking with Piet and Martin

Filed under: Uncategorized — bigdaveroberts @ 11:26 pm

Spent a very pleasurable evening a couple of nights ago with a couple of Oracle aces.

(Martin Widlake – yet another oracle blog and Piet De Visser – Simple Oracle DBA @ The farm

Much of the time was spent discussing how our careers were evolving and the reasons for that.

I have come late in my life to the skill of networking.

I have tended to concentrate always on my harder technical skills, essentially putting most effort into developing my strengths rather than trying to ameliorate my weaknesses.

However, several years ago, having been in a secure job for several years supporting a legacy application, it became apparent that my job was not as secure as I believed.

It was at that point I started thinking strategically and laterally with regards my career.

My problems included: outdated technical skills, not being a spring chicken in the IT industry, lack of visibility at my current employer and a prejudice against the skill set that I had with my customer. (I might edit this post later to add more problems!)

The lack of visibility at my employer was the result of coming in under TUPE regulations and being based at a site that was convenient for me and my customer, but where there were almost no other employees with a skill set similar to mine. (It was primarily a marketing and training hub.)

I had recently read about exogenous growth theory beloved by Gordon Brown and I established a strategy!

I stopped spending money as far as I could.
I started studying for an OCP qualification.
I bought as expensive new suit.
I joined the UKOUG and tried to attend as many SIGs as possible.
I started networking, primarily by attending university alumni events but also at UKOUG events.
I started this blog.

Of the above, I suspect that it was the OCP certification that has had most value in the initial relaunch of my career. Although I believe that after I was made redundant,  the fact that I spent part of my own redundancy money to pay for the required training to achieve this qualification was as valuable as the qualification itself.

Networking to my knowledge, was the least value and yet I have continued to pursue this even after securing myself a new role.

Ultimately, while networking hasn’t to my knowledge advanced my career, it has proved extremely pleasurable. I have developed new friendships, gained personal insight and met people with completely different experiences to myself. (Say for example, an ex-lifemodel and someone who had seen Oswald Moseley at Birmingham town hall.)

So, this is a post encouraging you to network in spite of the fact that it has to my knowledge not achieved for me the goals that I set for myself when I started.

Ultimately I’ve achieved other goals and enjoyed them vastly along the way.

My time spent with Piet and Martin constitute a small but significant part of that pleasure!

December 10, 2012

ukoug conference report: Dave Ensor

Filed under: Uncategorized — bigdaveroberts @ 9:53 pm

I only became aware of Mr Ensor when I read his chapter in the book: Oracle insights – tales of the Oak table.(


The chapter lists and explains the significance of the major new features in each release of Oracle.

I was at the time working on the support of two oracle based applications, which at the time presented me with baffling architectural eccentricities.

One was a document management system where the client application didn’t access the database directly, but rather made calls to an API implemented on the middle tier that had several daemon processes that would execute the required SQL on your behalf. I suspected that the application had been designed in that manner to better facilitate working with multiple database back ends.

The other held large chunks of PL/SQL in Long columns in the database. It then included an OCI*C daemon process that was passed messages via a DBMS_PIPE would then extract the appropriate PL/SQL code, perform parameter substitution, execute the PL/SQL and return the results via a table. This was again baffling to me, why not use stored procedures?

Both of these architectural mysteries were resolved by Dave Ensors chapter. While both applications ran on Oracle8i, it was apparent that their architecture was much older.

In Oracle 5, due to memory address limitations it was only possible to have 40 concurrent contentions to the database. Thus to support more users, the user SQL had to be multiplexed across a limited number of connections.

Similarly in Oracle 6 PL/SQL was introduced, but without a standard way of storing PL/SQL in the database. (Procedures and functions wouldn’t come till Oracle 7.)

Thus Mr Ensor explained to me the architecture of the applications I was supporting.

Dave Ensor attended last years Oak table Sunday at the UKOUG conference and participated in a panel discussion there. He also visited All bar One afterwords, but only briefly, and I missed my opportunity to thank him for the insight he had given me.

This year he didn’t attend either the conference or the Pre-conference OAK table Sunday event.

However he did visit All bar One and I had my opportunity to thank him for his contribution to TFTOT.

From his recollection, I was the first person to ever thank him for that specific piece of work, he had been asked to produce 20 pages, produced 120 and was then negotiated down to 70ish.

I suppose writing about older versions of Oracle isn’t necessarily sexy and on that basis this commensurate piece of work hasn’t received due recognition however if you support an application with a long history, you may do well by getting hold of a copy of this book and reading his chapter!

NB. the book also includes other excellent contributions and chapters!

November 18, 2012

11g forms error

Filed under: 11g,Oracle forms — bigdaveroberts @ 1:21 pm

After migrating to 11g we encountered the following error in 2 of our forms after migration to 11g:

Error 801 at line 0, line 0
internal error [phd_get_defn:DI_U_NAM_RHS]
Error 908 at line 0, column 0
The stored format of <schema name>.<Procedure name> is not supported by this release.

I believe that the issue related to compiling in form code that called database packages that had dependencies in other databases.

But that isn’t important, there was one hit on the OTN forum that correctly pointed me at the correct Metalink article and patch:

So the problem is described in article 1058803.1 and resolved by 7708340.

So ultimately the problem doesn’t seem to require a blog post.

There was however one anomaly  the patch is a database patch and the read-me implied that the patch needed to be applied to the Weblogic server also the patch was relatively speaking large.

I have to admit I was highly dubious about applying a database patch to the middle tier so I went ahead and applied the patch to my development PC, and to my great surprise, it worked.

It also appears that technically you don’t need to apply it to the middle tier, it simply needs to be applied to the PC on which the forms are compiled, although obviously it would be good practice to keep the development PCs and server environments in sync with the live environment.
So sometimes, however unlikely it sounds, Oracle instructions are sometimes accurate straight out of the tin!

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