Free MIT Computer Science Classes Online

This is very cool:

There are a bunch of nice computer science classes online from mit: Free online MIT computer science classes

Here is an introductory computer science class: Intro to computer science

Here is a graded version of the same class on edX: Graded version of MIT intro CS class starting June 10th.

edX does not have as many computer science classes but edX may motivate students because edX classes include grades and certificates for those who (more...)

Delphix announces masking acquisition

I’m excited to announce the first acquisition by Delphix (portending many to come). Dephix has just acquired the data masking company  Axis Technology Software. Delphix is integrating the Axis masking technology into the core Delphix product. Masking is a feature that 9 out of 10 customers have asked for after buying Delphix. Delphix eliminates the data cloning bottleneck  for application development environments and naturally the next concern that arises is how to mask the data from production (more...)

Writing tips and techniques

It’s been a while since I’ve posted anything on my blog, and this is a slightly different post to the rest, as it’s not technical in any way…  Instead it’s a quick post about a series of fantastic writing tips and techniques posted recently, from my good friend Tim Hall at ORACLE-BASE.  I’ve tweeted a few of these

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SQL performance, Part III. Data storage strategies

Imagine that you’re on a desert island where some pirates hid their treasure. You don’t know where exactly it is hidden, but you want to find it. How should you approach this – e.g. should you dig randomly? Or should you follow some sort of a system – and if yes, then which?

I think most readers have smelled a trap right away (it’s not a very sophisticated trap anyway) – of course it (more...)

Delphix Data as a Service (DaaS)

The capabilities of Delphix can be differentiated from snapshot technologies through the following hierarchy:


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  1. Data as as Service (DaaS) (Delphix approach to data management)
  2. Virtual Data (end-to-end collection and provisioning of thin clones)
  3. Thin Cloning
  4. Storage Snapshots
On top we have the most powerful and advanced data management features that enable fast, easy, secure, audit-able data flow through organizations.
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DaaS is built on top of other technologies. On the bottom we have the minimal building (more...)

First Impression for Evodesk Desktop Unboxing

Disclaimer: I am not being paid by anyone to write positive or negative review.

Opinions are my own based on my limited engineering background.

First, packaging is somewhat poor and could be much better for a desk costing close to $1,000 ($886 for my configuration).

Tape coming off.

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I hope my desktop is okay.

badpackaging1

Taking a look inside. Is that a tiny scratch I see?

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After opening the desktop, this is the torn location – (more...)

5 Minute JavaScript #17: some and every

In the previous blogpost we discussed the map method on arrays in JavaScript. We still have some useful methods the go. Next in line are the some and every methods. These methods are similar and can be very useful when validating data.

var isEven = function (n) { return n % 2 === 0 };
var areAllEven = [2, 4, 6].every(isEven);
var someEven = [1, 2, 3].some(isEven);

The every method will check if (more...)

Simple C program for testing disk performance

I dug up a simple C program that I wrote years ago to test disk performance.  I hesitated to publish it because it is rough and limited in scope and other more capable tools exist. But, I have made good use of it so why not share it with others?  It takes a file name and the size of the file in megabytes.  It sequentially writes the file in 64 kilobyte chunks.  It opens the (more...)

SQL Performance, Part II — Disk I/O: metrics and scales

While query performance depends on a large number of things, overall scale of query performance for a given database is generally set by disk I/O speed. The most common type of a storage device used in databases is still a hard disk drive (HDD), so let’s consider how it works.

HDD uses magnetic state of a very small region on a disk to encode “0” or “1” (i.e. carry 1 bit of information). A (more...)

SQL Performance, Part I. Data access efficiency.

Database performance optimization deals with the problem of reducing time (and/or other resources) required to complete database queries by resolving various inefficiencies. There are many kinds of performance issues, and they can be categorized in many different ways. One important way is by scope: statement-level or instance-level. Instance-level performance tuning (which we are not covering in this mini-series) deals with such problems as excessive parsing, cache efficiency, concurrency etc. Statement-level performance tuning deals mostly with (more...)

Giving back

Occasionally, I receive requests to explain stuff I talk about in my blog posts on a level accessible to beginners. Unfortunately, it’s not always possible to do so. You start to explain one little thing, and then you realize that in order to understand that thing, one would to understand a dozen other little things, and before you know it, instead of writing a short blog post you find yourself writing something of the size of (more...)

Top 6 production database mistakes that could be slowing down your system

Oracle Is Easy, a blog written by <a href="http://www.smartdogservices.com" SmartDog Services

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After more of 14 years of experience working with Oracle Databases of different sizes, levels of activity and critical importance, I know a thing or two about production databases. No matter the size of the database or the complexity of the product that is working with the database, there are always some common settings that DBAs are missing and can adjust improve (more...)

db file parallel read on Linux and HP-UX

In my previous post I described how I could not explain why I got better db file parallel read wait times in a test on Linux than I got running the same test on HP-UX.  I have discovered that the Linux wait times were better because Linux cached the data in the filesystem cache and HP-UX did not.

Neither system used direct I/O for the tests so both could cache data in the filesystem cache. (more...)

5 Things I wish I knew about APEX when I just started (part 3)

Build Options

Imagine having to release an apex application, but you don’t want some parts released in to the production environment yet, because they are unfinished, or not tested. Or you want to disable a module in your application for some reason.

Apex provides a solution for this called build options.

You can find the build options under shared components > logic > build options

Let’s create 2 build options:

The first one will keep (more...)

db file parallel read faster on Linux than HP-UX?

I am still working on comparing performance between an HP-UX blade and a Linux virtual machine and I have a strange result.  I tried to come up with a simple example that would do a lot of single block I/O.  The test runs faster on my Linux system than my HP-UX system and I’m not sure why.  All of the parameters are the same, except the ones that contain the system name and filesystem names. (more...)

Simple test of DB server CPU speed

I’m trying to compare two types of database servers and it looks like one has a faster CPU than the other.  But, the benchmark I have used runs a complicated variety of SQL so it is hard to really pin down the CPU performance.  So, I made up a simple query that eats up a lot of CPU and does not need to read from disk.

First I created a small table with five rows:

 (more...)

Planning, Implementing and Nurturing Your Failure Analysis Codes in Oracle EAM

Oracle Is Easy, a blog written by <a href="http://www.smartdogservices.com" SmartDog Services

It has been said that the goal of a good Maintenance Manager should be the elimination of his Maintenance Department. My opinion is that phrase should be amended to read “A good Maintenance Manager’s goal should be the elimination of Corrective Maintenance.” Since machines and software are not perfect one hundred percent across the board, a more realistic goal is to (more...)

In Search of Standing Desk

I came across Evodesk Standing Desk Review
http://www.workwhilewalking.com/evodesk-standing-desk-review

Could not resist the temptation but reach out to @TreadmillDesker
You bark loud but how is ThermoDesk ELITE better EVODESK other than motor? $477=1333-886 is a lot for a motor. Let’s see pic.

Here is the respond I got back.
Thanks for the question! lab test of the Evo’s base concluded: slower speed, louder motors, and instability at taller heights.

Notice the respond was very (more...)

Google Search Appliance GSA Version 7.4 Released

Wanted to drop a quick note here that Google released the latest version of the Google Search Appliance software last week. That brings the most current version up to 7.4.0.G.72 and officially end of life’s the 7.0 version of the appliance software.

New features from the support site posting:

  • Seamless Integration with Microsoft: we’re releasing our SharePoint and Active Directory 4.0 connectors out of beta. These connectors provide improved (more...)

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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What is Oaktable World ? Oaktable World is a day organized by members of the Oaktable network. The Oaktable network is a network of Oracle database tuning geeks. Among the members are Tanel Poder, Jonathan Lewis, Cary Millsap etc.  Oaktable network was created by Mogens Nørgaard back in 2001 or so and Mogens started (more...)