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July 2017

Little Things Doth Crabby Make – Part XX – Man Pages Matter! Um, Still.

It’s been a while since I’ve posted a Little Things Doth Crabby Make entry so here it is, post number 20 in the series. This is short and sweet.

I was eyeing output from the iostat(1) command with the -xm options on a Fedora 17 host and noticed the column headings were weird. I was performing a SLOB data loading test and monitoring the progress. Here is what I saw:

Taking on a new position

After a couple of months of looking around, a good friend (that I now owe a few beers to!) reached out to me to tell me he’d recommended me for a position with a company based out of Brisbane (well, the Australian office is there anyway!) The very next day, after a couple of interviews, I decided the company he recommended would be a great fit from both a technical and a team perspective, and we had a verbal agreement that I would start work with them on July 24th. Now that the paperwork has officially been signed, I can tell you that I’ve taken on a role as a Senior Managed Services Consultant with Red Stack Tech. There are two things that attracted me to the role:

Apache Impala Internals Deep Dive with Tanel Poder + Gluent New World Training Month

We are running a “Gluent New World training month” in this July and have scheduled 3 webinars on following Wednesdays for this!

The first webinar with Michael Rainey is going to cover modern alternatives to the traditional old-school “ETL on a RDBMS” approach for data integration and sharing. Then on the next Wednesday I will demonstrate some Apache Impala SQL engine’s internals, with commentary from an Oracle database geek’s angle (I plan to get pretty deep & technical). And in the end of the month, a Gluent customer Vistra Energy will talk about their journey towards a modern analytics platforms.

All together this should give a good overview of architectural opportunities that modern enterprise data platforms provide, with some technical Apache Impala hacking thrill too!

Offload, Transform & Present – The New World of Data Integration

12.2 New Feature: the FLEX ASM disk group part 2

In the first part of this series I explained the basics and some potential motivation behind the use of ASM Flex disk groups. In this part I would like to complete the description of new concepts.

New Concepts related to FLEX ASM Disk Groups

With the Flex disk group mounted, the next steps are to create a few new entities. First, I want to create a Quota Group. The Quota Group – as the name implies – will enforce quotas for entities residing within it. It is optional to add one yourself, Oracle creates a default Quota Group for you that does not enforce storage limits. As you will see later, the default Quota Group will be assigned to all new databases in the Flex ASM disk group.

ODTUG’s KSCOPE 2nd Annual Geekathon

After returning from KSCOPE two weeks ago, I was again approached to be a judge this year on the Geekathon 2017.

Enough with AFIEDT.BUF

You are in SQL*Plus. You entered a command and urgh, there was a typo. No worries, you bring up the command in an editor by typing:

SQL> ed

This opens up an editor, such as notepad.exe in Windows or vi in Unix, etc. And it puts the last SQL you entered in a file, oddly named, afiedt.buf. You don't like it and you want a name easier to type. Is it possible? Of course.

History of Afiedt.Buf

First a little bit of background information on the odd name. SQL*Plus as a tool evolved from another tool Oracle provided a long, long time ago, called--rather uncreatively--User Friendly Interface, or UFI. When the editor wanted to bring up a file for editing, the file had to be given a name unique enough so as not to conflict with anything else. Therefore the file was named ufiedt.buf, which roughly indicated UFI Editor Buffer.

12.2 Introduction to Real-Time Materialized Views (The View)

Although I usually focus on index related topics, I’ve always kinda considered Materialized Views (MVs) as an index like structure, which Oracle can automatically update and from which Oracle can efficiently retrieve data. The cost of maintaining a Materialized View Log is not unlike the cost of maintaining an index structure, the benefits of which […]

Postgresql block internals, part 3

This is the third part in a series of blogposts about how postgresql manages data in its blocks (called ‘pages’ in postgres speak). If you found this post and did not read the previous ones, it might be beneficial to read block internals (part 1) and block internals, part 2 first. In these blogposts I’ve shown how heap and index pages look like, and how these can be investigated, including looking at the raw block information.

This blogpost is intended to show the effects on pages when DML happens. This is inherently different from my personal reference of database implementation, which is the oracle database.

Setting APPINFO in SQL*Plus

Ever used the MODULE column of V$SESSION view? If you haven't, you are missing out on a very important piece of instruemntation code built right into the Oracle database session management. This allows you to assign a completely arbitary name, as you would see will properly describe for your application. Later when you want to identify that session, you can check the MODULE column in V$SESSION. Even though the userid is the same for all these sessions; the module column will help you identify the session.

Let's see how it works by a little example. Here is how you check the module information.


select module
from v$session
where username = 'SYS'

MODULE
-----------------------------
sqlplus.exe
sqlplus.exe

In both cases the MODULE column shows the same value. You can set he module to a more descriptive name by issuing this command:

12.2 ACFS compression, part I

One of the new 12.2 features is the ability to transparently compress ACFS filesystems.

Compression is enabled using acfsutil utility:

[root@raca1 ~]# acfsutil -h compress on
Usage: acfsutil [-h] compress on [-a ]
- Set default compression algorithm
Currently only 'lzo' available
- Enable compression on volume

Clearly there is support for more compression algorithms to be added in the future but right now only lzo is supported.

Let's go ahead and enable compression on the ACFS filesystem I have:

[root@raca1 ~]# acfsutil compress on /u02/oradata

Compression status can be checked using acfsutil info fs:

[root@raca1 ~]# acfsutil info fs /u02/oradata
/u02/oradata
ACFS Version: 12.2.0.1.0