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November 2015

Little Things Doth Crabby Make – Part XVIV: Enterprise Manager 12c Cloud Control 12.1.0.5 Install Problem.

This is a short post to help out any possible “googlers” looking for an answer to why their 12.1.0.5 EM Cloud Control install is failing in the make phase with ins_calypso.mk.

Note, this EM install was taking place on an Oracle Linux 7.1 host.

The following snippet shows the text that was displayed in the dialogue box when the error was hit:

Histograms

A short video that I did at the OTN lounge at RMOUG a couple of years ago has just been posted on YouTube. It’s about the improvements that appear in histograms in 12c. I’ll move this link into a more suitable posting in the near future.

 

Pragma UDF – Some Current Limitations

There are currently some limitations to when pragma UDF will speed up your calls to PL/SQL functions from SQL.

In my post introducing the new pragma UDF feature of Oracle 12c I explained how it can be used to reduce the impact of context switching when you call a PL/SQL function from SQL.

In my example I showed how running a SQL-only SELECT statement that formatted a name for display over 100,000 records took 0.03 seconds went up to 0.33 seconds when the formatting SQL was put in a user defined PL/SQL function. This impact on performance is a shame as it is so beneficial to encapsulate business logic in one single place with PL/SQL. Stating that the PL/SQL function is a user defined one with the pragma UDF option reduced the run time to 0.08 seconds – which is removing most of the context switching overhead. Check out the prior post for full details.

SANGAM15 : It’s nearly here!

In about a week I will be starting my journey to Hyderabad to speak at SANGAM15, the big AIOUG event for India.

I’ve been to India before, when I did the Yathra tour, but this is my first SANGAM event, so I don’t really know what to expect. :)

The plan is:

Delphix versus Storage Snapshots

4333881004_ff0835e8cc_zphoto by Gonzalo Iza

This article lists some of the key capabilities that Delphix provides over and above Storage Snapshot based cloning solutions to meet the increasing business demand for Agile Development.

I’ve blogged about this before in

VirtualBox 5.0.10

VirtualBox 5.0.10 has been born.

Downloads and changelog in the usual places.

There has been a bit of a discussion on Twitter today about the pros and cons of upgrading VirtualBox. I run VirtualBox on Windows 7 at work and Linux and Mac at home. Unless I’m travelling, I pretty much upgrade straight away. In recent history I only remember one time a patch has caused me problems and forced me to back it out. It seems other people on Twitter have had more issues than me.

I made the jump from VirtualBox 4 to 5 immediately and haven’t suffered at all.

Troubleshooting Another Complex Performance Issue – Oracle direct path inserts and SEG$ contention

Here’s an updated presentation I first delivered at Hotsos Symposium 2015.
It’s about lots of concurrent PX direct path insert ant CTAS statements that, when clashing with another bug/problem, caused various gc buffer busy waits and enq: TX – allocate ITL entry contention. This got amplified thanks to running this concurrent workload on 4 RAC nodes:
When reviewing these slides, I see there’s quite a lot that needs to be said in addition to what’s on slides, so this might just mean a (Powerpoint) hacking session some day!

Troubleshooting Another Complex Performance Issue – Oracle direct path inserts and SEG$ contention

Here’s an updated presentation I first delivered at Hotsos Symposium 2015.

It’s about lots of concurrent PX direct path insert ant CTAS statements that, when clashing with another bug/problem, caused various gc buffer busy waits and enq: TX – allocate ITL entry contention. This got amplified thanks to running this concurrent workload on 4 RAC nodes:

When reviewing these slides, I see there’s quite a lot that needs to be said in addition to what’s on slides, so this might just mean a (Powerpoint) hacking session some day!

Troubleshooting Another Complex Performance Issue – Oracle direct path inserts and SEG$ contention

Here’s an updated presentation I first delivered at Hotsos Symposium 2015.
It’s about lots of concurrent PX direct path insert ant CTAS statements that, when clashing with another bug/problem, caused various gc buffer busy waits and enq: TX – allocate ITL entry contention. This got amplified thanks to running this concurrent workload on 4 RAC nodes:
When reviewing these slides, I see there’s quite a lot that needs to be said in addition to what’s on slides, so this might just mean a (Powerpoint) hacking session some day!

Which version of Oracle Linux should I pick for Oracle server product installations?

linux-tuxOracle certifies many of their latest products for installation on Oracle Linux 6 and 7, so I guess the obvious question is, which should you pick?

I tend to have a dual approach to this. I always use the latest versions of everything for my play kit, but I tend to be a little conservative for production deployments, preferring to use the OS version the product was developed against. I’ve noticed Oracle Cloud and some VM templates are still using Oracle Linux 6, which makes me think Oracle are being a little conservative too.