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December 2014

Cardinality Change

Here’s an entertaining little change across versions of Oracle, brought to my attention by Tony Hasler during UKOUG Tech 14. It’s a join cardinality estimate, so here are a couple of tables to demonstrate the issue – the only columns needed are the alpha_06 columns, but I reused some code from other demonstrations to create my test case, so there are lots of irrelevant columns in the create table script:

Days -1 and 0 of UKOUG Tech 14

The UKOUG user group conference is one conference I have wanted to get to for a long time, but never managed to before. This year, with the change in job roles to being a database architect in the DBaaS team within the Enterprise Manager product management group, I finally got the go ahead to submit some papers. I was notified some time back that one of them had been accepted (Snap Clone) and one shortlisted (DBaaS), and I was asked by one of my colleagues to help out with the Enterprise Manager round table. Just before I came over to the UK, the UKOUG folks asked me to also present the DBaaS presentation, so now I have something on each of the 3 days the conference is scheduled for.

Announcing XtremIO Performance Engineering Lab Report: Facts About Redo Logging And NAND Flash.

I invite you to please read this report.

NAND Flash is good for a lot of things but not naturally good with write-intensive workloads. Unless, that is, skillful engineering is involved to mitigate the intrinsic weaknesses of NAND Flash in this regard. I assert EMC XtremIO architecture fills this bill.

Regardless of your current or future plans for adopting non-mechanical storage I hope this lab report will show some science behind how to determine suitability for non-mechanical storage–and NAND Flash specifically–where Oracle Database redo logging is concerned.

Please note: Not all lab tests are aimed at achieving maximum theoretical limits in all categories. This particular lab testing required sequestering precious lab gear for a 104 hour sustained test.

Munching the Squarespace Hamburger

Many Squarespace templates indicate mobile menus by the so-called hamburger icon. It's the three-bar icon in the upper-left corner of Figures 1. Use of the hamburger is controversial; some believe it unintuitive; some prefer a button labeled "Menu". Templates like Five and Marquee make it easy to substitute a menu button like you see in Figure 2.

Munching the Squarespace Hamburger

Many Squarespace templates indicate mobile menus by the so-called hamburger
icon. Some argue that the hamburger is unintuitive. Templates like Five and
Marquee make it easy to avoid the burger...



Read the full post at www.gennick.com/database.

Ten Year Site Anniversary

I realized yesterday that this site has pasted his ten year anniversary. In all funny…

Closure

It’s been a long time since I said anything interesting about transitive closure in Oracle, the mechanism by which Oracle can infer that if a = b and b = c then a = c but only (in Oracle’s case) if one of a, b, or c is a literal constant rather than a column. So with that quick reminder in place, here’s an example of optimizer mechanics to worry you. It’s not actually a demonstration of transitive closure coming into play, but I wanted to remind you of the logic to set the scene.

Announcing SLOB 2.2 : Think Time and Limited-Scope User-Data Modification

This is a hasty blog post to get SLOB 2.2 out to those who are interested.

Where To Get The Kit

Please visit kevinclosson.net/slob

About The New Kit

In addition to doing away with the cumbersome “seed” table and procedure.sql, this kit introduces 5 new slob.conf parameters. By default these parameters are disabled.

This SLOB distribution does not require re-executing setup.sh. One can simply adopt the kit and use it to test existing SLOB databases. The following explains the new slob.conf parameters:

DO_UPDATE_HOTSPOT=FALSE

When set to TRUE, modify SQL will no longer affect random rows spanning each session’s schema. Instead, each session will only modify HOTSPOT_PCT percent of their data.

my Time/Task/Goal/Habit (TTGH) management

There was a post last night on oracle-l on the topic of task/project/time management, and I’m a big fan of productivity
hacks and the whole GTD idea or method http://en.wikipedia.org/wiki/Getting_Things_Done. The reason for adopting this method is I’ve been on consulting business my entire career and I always get swamped with a lot of work from multiple
customers or research stuff and it’s really difficult to prioritize and focus without a system. The same thing I learned how to speed read (see tony buzan book) because there’s just not enough time and you want to learn as much as you can. The bottom line is you want to be efficient.

So I thought of sharing my way of dealing with this in general…

OMS and OMR Performance- Part III, Metrics Page

Before heading off to UKOUG’s Tech 14 conference, thought I would jump back from the Agents performance page and look into the very important page in the Oracle Management Service, (OMS) and Oracle Management Repository, (OMR) regarding metrics.  Standard metrics collection is demanding in itself, so when we add plugins, metric extensions and manual metric collection changes, it’s important t