April 2015

No Data Loss without Synchronous Network

I don’t usually write about specific products; but once in a while I encounter something worth talking about, especially if it addresses a very common issue anyone with datacenter management responsibilities will understand: avoiding the unavoidable loss of last minute data changes in database after a disaster but without expensive synchronous replication. This product solves that problem with an innovative out of the box approach. The product is Phoenix Systems from Axxana.

Basic (newbie) install CoreOS on VirtualBox – Getting started with Docker

I got intrigued by this Dutch article mentioning Docker and CoreOS. So on this Saturday,…

Collaborate ’15

It’s time for another phenomenal Collaborate conference next week, made even more fabulous by the fact that I’ll be there for the first time! :) For some reason, Collaborate is one of the few big user group conferences I haven’t made it to before, so when my boss asked me to go and present at it I leapt at the chance.

Originally, I had one presentation timeslot, but then Alex Gorbachev of Pythian / Oak Table fame noticed I was attending and asked me to do a couple of slots at Oak Table World on the Wednesday. Then the organizers had a drop-out and asked Seth Miller and I to fill it in, so my dance card is starting to look a bit more full! So dates and times for when I will be presenting currently stand at:

Counting

There’s a live example on OTN at the moment of an interesting class of problem that can require some imaginative thinking. It revolves around a design that uses a row in one table to hold the low and high values for a range of values in another table. The problem is then simply to count the number of rows in the second table that fall into the range given by the first table. There’s an obvious query you can write (a join with inequality) but if you have to join each row in the first table to several million rows in the second table, then aggregate to count them, that’s an expensive strategy.  Here’s the query (with numbers of rows involved) that showed up on OTN; it’s an insert statement, and the problem is that it takes 7 hours to insert 37,600 rows:

Avoiding the COMMIT bomb!

I’m an Oracle dinosaur, so I like using SQL Plus.  Its simple, fast, comes with every version and installation and platform, and I’m very familiar with it.  (And who knows, it might still be at the forefront of the Oracle development teams!  http://www.slideshare.net/hillbillyToad/sqlcl-overview-a-new-command-line-interface-for-oracle-database )

But there is one important thing I always take care of when I’m using SQL Plus, and it’s easiest to explain with an example.

You start off by wanting to delete a couple of rows from a critical table as part of a patching process.  You type this:

Video Tutorial: XPLAN_ASH Active Session History - Part 5

#333333; font-family: Verdana, Arial, sans-serif; font-size: 13px; line-height: 16.8999996185303px;">The next part of the video tutorial explaining the XPLAN_ASH Active Session History functionality continuing the actual walk-through of the script output.
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DBAKevlar at Collaborate 2015

Here’s a quick guide to my schedule of sessions at IOUG Collaborate 2015 for this year.

Data Cloning and Refresh

For some time now, I’ve been creating blog posts that walk you through using some of the Enterprise Manager technology to perform specific tasks. For example, there’s one here on setting up Chargeback in EM 12.1.0.4. I’ve never been really satisfied with the way these blog posts turn out, as to document a step by step process like this takes lots of screenshots and you end up with a post that’s a mile long. It also gives the impression that doing something can be quite complex, when in fact it might only take a few minutes to perform all those steps.

Tuning Database XQuery Statements (2)

So we concluded the post “Tuning Database XQuery Statements (1)” with the following SQL statement…

Oaktable World Las Vegas April 15, 2015 at Collaborate

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Wednesday April 15 at Collaborate 2015 Las Vegas room Mandalay K
For more information see Pythian’s Blog post.

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