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March 2014

OUG Ireland 2014

As you probably know by now I was at OUG Ireland yesterday.

It was a pretty early start for me. I needed to be up by 03:30 to get a taxi to the airport, but fear of missing my flight meant I was awake from about 01:00 onward. My taxi driver wanted to talk about some rather strange stuff during the ride. A conflicted individual I guess…

The Ryanair flight across to Dublin went smoothly enough. There were 18 people on a 737, so I’m guessing that flight didn’t cover the staff costs, since I paid £30 for a return flight. Once at Dublin I took the AirLink bus for 10 euros, which dropped me outside The Convention Centre Dublin.

What is the difference between logical and physical corruption in Oracle?

When we talk about logical corruption, there are two different failure states that fall under this label:

Oracle Cross Platform Provisioning: Magic from the Mess

Linux is taking over the workloads from the shrinking market share of

Linux strace doesn’t lie after all.

strace is a linux utility to profile system calls. Using strace you can see the system calls that a process executes, in order to investigate the inner working or performance. In my presentation about multiblock reads I put the text ‘strace lies’. This is NOT correct. My current understanding is that strace does show every system call made by an executable. So…why did I make that statement? (editorial note: this article dives into the inner working of Linux AIO)

Delphix 4.0 released ! The Modernization Engine

Delphix is amazing technology. I’ve been at Delphix for almost 4 years. The first year I was at Delphix was the first year Delphix was released on the market. Even from that first release Delphix revolutionized how we managed and think about data. Data goes from an onerous massive burden to instead a  fast, easy,  powerful resource. As one customer put it data goes from being your enemy to being your friend (and a powerful one at that).

Parallel Plans

I’ve popped this note to the top of the stack because I’ve added an index to Randolf Geist’s series on parallel execution skew, and included a reference his recent update to the XPLAN_ASH utility.

This is the directory for a short series I wrote discussing how to interpret parallel execution plans in newer versions of Oracle.

The Language of Pseudoscience

If Google were to characterise me based on my YouTube views, they would probably list me as some major conspiracy theory junkie. I watch a lot of conspiracy theory rubbish on YouTube, but for me it is light entertainment. I find it amusing to see how they try to present a bunch of random nonsense as science. Watch any of this stuff and you will hear the same types of phrases again and again…

Gartner & Delphix : DELIVER APPLICATIONS with better, faster data

Screen Shot 2014-03-10 at 12.21.07 PM

Orignal PDF for this content available here.

Duplicate database

One of the people attending my seminar in Munich last week has emailed me some details about a nasty little surprise you may get if you’re thinking about TSPITR (tablespace point in time recovery), and happen to have a few materialized views in your database.

You might have wanted to use the “duplicate target database”  from rman with the “skip tablespace” option to create a duplicate database, excluding tablespaces that you’re not interested in, if you needed to recover a particular tablespace (or set of tablespaces) to a specific point in time.  (Once you’ve done that you can extract the data that you want and then discard the duplicate database). But there’s a requirement for recovery is that the set of tablespaces should be “self-contained”; but what does “self-contained” mean ?

Parallel Execution – 5

In the last article (I hope) of this series I want to look at what happens when I change the parallel distribution method on the query that I’ve been using in my previous demonstrations.  This was a query first introduced in a note on Bloom Filters (opens in a separate window) where I show two versions of a four-table parallel hash join, one using using the broadcast distribution mechanism throughout, the other using the hash distribution method. For reference you can review the table definitions and plan (with execution stats) for the serial join in this posting (also opens in a separate window).