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September 2014

VirtualBox 4.3.16

virtualboxVirtualBox 4.3.16 has arrived. The downloads and changelog are in the usual places.

Although 4.3.14 worked fine on OS X and Linux, I skipped it on Windows because it just wouldn’t start a VM. That issue is allegedly fixed in this release. The changelog includes the following entry.

Windows hosts: fixed startup problems on certain Windows hosts due to conflicts with anti-virus software (4.3.14 regression, bug #13187)”

Happy days! :)

Cheers

Tim…

Oracle Midlands Event #5

Just a quick reminder. Oracle Midlands Event #5 is next Tuesday evening. Here is the information from the website.
om5

I’ll see you there!

Cheers

Tim…


Oracle Midlands Event #5 was first posted on September 10, 2014 at 9:48 am.
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Intra-Database IORM in action

I have been teaching the Enkitec Exadata Administration Class this week and made an interesting observation I thought was worth sharing with regards to IO Resource Management on Exadata.

I have created a Database Resource Manager (DBRM) Plan that specifically puts a resource consumer group to a disadvantage. Actually, quite severely so but the following shouldn’t be a realistic example in the first place: I wanted to prove a point. Hang-on I hear you say: you created a DBRM plan-the post has IORM in the subject though: what gives? Please allow me to explain.

Exadata offers 3 different ways to implement IORM to the keen engineer:

Quiz Night

I have a table with several indexes on it, and I have two versions of a query that I might run against that table. Examine them carefully, then come up with some plausible reason why it’s possible (with no intervening DDL, DML, stats collection, parameter fiddling etc., etc., etc.) for the second form of the query to be inherently more efficient than the first.

Zone Maps On Commit Refresh Oddities

One of the ways Zone Maps can be refreshed when the underlying table data is changed is fast on commit. This is similar to how materialized views can be refreshed with the exception that a Zone Map does not need a materialized view log to do so.

It can also lead to some peculiar side effects.

Test setup

Let's begin by creating a test table with the on commit refresh materialized zone map:





SQL> create table t pctfree 95 clustering by linear order (n) as
2 select level n, rpad('x', 200, 'x') v
3 from dual
4 connect by level <= 5000;

Table created

SQL> create materialized zonemap zm$t refresh fast on commit on t (n);

Done

SQL> select * from zm$t order by 1;

ZONE_ID$ MIN_1_N MAX_1_N ZONE_LEVEL$ ZONE_STATE$ ZONE_ROWS$
---------- ---------- ---------- ----------- ----------- ----------

Dear “Pro-life”: I am against abortion. But I am not against choice

If you run for office, you’ll get loaded questionnaires that essentially insist you sign up to overturn Roe v Wade. (And from the other side that you’ll sign up against things like the Hobby Lobby ruling, when the real issue is that individuals or families, not corporations, should control their own health care insurance choices.)

And let’s decode a little bit, since even the names of the movements are a lie: “Pro-life” means “I want to make abortion illegal.”

“Pro-choice” means I want the government to routinely fund abortion and make it a popular choice. I’m aligned with clinics that provide abortions and we tout the advantages to your life style of not having a child to raise or going through the inconvenience of carrying a child to term to be adopted.

ASSM Truncate.

Here’s one that started off with a tweet from Kevin Closson, heading towards a finish that shows some interesting effects when you truncate large objects that are using ASSM. To demonstrate the problem I’ve set up a tablespace using system allocation of extents and automatic segment space management (ASSM).  It’s the ASSM that causes the problem, but it requires a mixture of circumstances to create a little surprise.

Openworld bound..

I’ll be in Openworld again this year, and have a couple of speaking slots…

I’ll talk about new features for developers in 12c on Sunday, Sep 28, 2:30 Moscone South 303

https://oracleus.activeevents.com/2014/connect/sessionDetail.ww?SESSION_ID=2244

and of course, at the awesome Oaktable world..

http://www.oraclerealworld.com/oaktable-world/agenda/

Drop in, learn some cool things, or just pop up and say Hello!

The #SAFE_DEAL: On the road to Equal Taxation with a baseline of the poverty level

Twenty-two years ago, when I previously ran for US Senate and began writing about reviving the idea of full support of persons legally in the country to the poverty level, we were in much better overall financial shape. An actual maximum tax would have been possible with some budget discipline. Eventually and philosophically, I think that is still the goal. If everyone made enough money to pay an equal share of the country’s budget and still be above the poverty level, that is what we should do. The philosophy is clear: One Person, One Vote; One Person, One Tax.

Oracle IO wait events: db file sequential read

(the details are investigated and specific to Oracle’s database implementation on Linux x86_64)

Exadata IO: This event is not used with Exadata storage, ‘cell single block physical read’ is used instead.
Parameters:
p1: file#
p2: block#
p3: blocks

Despite p3 listing the number of blocks, I haven’t seen a db file sequential read event that read more than one block ever. Of course this could change in a newer release.