Making sense of direct path reads during primary key lookups

I recently made an interesting observation while monitoring database performance on an Oracle Enterprise Edition system. While looking at some ASH data (for which you must be licensed appropriately!) I came across direct path reads attributed to a select statement performing a primary key lookup. At first, this didn’t make much sense to me, but it’s actually intended behaviour and not a bug.

In this post I’m reproducing what I observed. I am using (more...)

Little things worth knowing: the latest public-yum-ol7.repo configuration file enables an upgrade to UEK R5

For a little while now I have been using Ansible for all installation/configuration tasks I do in the lab. I can’t really be bothered to do these things by typing commands anymore: once you get the hang of Ansible, you can develop an urge to automate everything. As part of my playbook installing the Oracle database on Oracle Linux, I replace /etc/yum.repos.d/public-yum-ol7.repo with the current version from Oracle’s server to make sure (more...)

Linux grub2 boot loader manipulation

This post is about how to manage grub2 in an easy way.

grub1

In the past, which is before linux EL7, the boot loader was grub, the grand unified bootloader (version 1). Things were very simple; if you installed another kernel (using rpm) it would add an entry to grub’s configuration in /boot/grub/menu.lst. If you wanted to change grub to boot that newly installed kernel by default you edit /boot/grub/menu.lst and set ‘default’ (more...)

Little things worth knowing: parallel Data Pump export in table mode

I haven’t used Data Pump in a little while but recently needed to do a bit of work involving this very useful utility to export a single table. I know that it is possible to export data in parallel using expdp, but I can’t recall the syntax for doing so off the top of my head when I need it. This post describes a potential approach to exporting a table in parallel. In the next (more...)

Ubuntu: if WLAN is gone after an update and lspci lists no wlan devices

On my ubuntu laptop after an update the WLAN networking was gone. First check was to boot into Windows and check wether the WLAN devices is still working:
The WLAN still worked with Windows, so the worst case (hardware error) did not hit me ;-)

So i switched back to Ubuntu and tried the following:

$ lspci -nnk | grep -iA2 net;
02:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express (more...)

Installing Ansible on Oracle Linux 7 for test and development use

There are a few alternative ways of installing Ansible on Linux, and the install guide for Ansible 2.7 (the current version at the time of writing) does a great job in explaining them all in detail.  There is a potentially easier way to get to a current Ansible version if you are using Oracle Linux 7, but it comes with a very important limitation. Let’s get that out of the way first.

You (more...)

OBUG Tech Days Belgium 2019 – Antwerp – 7/8-FEB-2019

Agenda: https://www.techdaysbelgium.be/?page_id=507

Dates: February 7 and 8, 2019

Location: http://cinemacartoons.be in Antwerp, Belgium

More information soon.

For people from the netherlands: this is easy reachable by car or by train! This is a chance to attend a conference and meet up with a lot of well-known speakers in the Oracle database area without too extensive travelling.

Python & Oracle 1

While Python is an interpreted language, Python is a very popular programming language. You may ask yourself why it is so popular? The consensus answers to why it’s so popular points to several factors. For example, Python is a robust high-level programming language that lets you:

  • Get complex things done quickly
  • Automate system and data integration tasks
  • Solve complex analytical problems

You find Python developers throughout the enterprise. Development, release engineering, IT operations, and support (more...)

Lab Correction

Anyone using the August 2018 Fedora image should note that I neglected to put the right transaction_upload2.csv file in the /u01/app/oracle/upload directory. You can fix that by navigating to the Lab 12 Instructions web page and click on the zip file link to download the correct file. You will see the following dialog asking whether you want to open the file with the Ark utility, click OK to continue:

After clicking OK to open (more...)

Bootstrapping a VM image in Oracle Cloud Infrastructure using cloud-init

At the time of writing Oracle’s Cloud Infrastructure as a Service (IaaS) offers 2 ways to connect block storage to virtual machines: paravirtualised and via iSCSI. There are important differences between the two so please read the documentation to understand all the implications. I need all the performance I can get with my systems so I’m going with iSCSI.

It’s the little differences

Using the paravirtualised driver couldn’t be easier: you boot the VM, and (more...)

Enhanced “validate” commands in Oracle’s Data Guard Broker 18c

If you are using an Oracle Database Enterprise Edition chances are that there is at least one environment in your estate making use of Data Guard. And if you are using Data Guard, why not use the broker? I have been using Data Guard broker for a long time now, and it has definitely improved a lot over the first releases, back in the day. I like it so much these days that I feel (more...)

Log in to Ubuntu VMs in Oracle Cloud Infrastructure

When I learned that Oracle was providing Ubuntu images in Oracle Cloud Infrastructure (OCI) I was a bit surprised at first. After all, Oracle provides a great Enterprise Linux distribution in the form of Oracle Linux. As a Ubuntu fan I do of course appreciate the addition of Ubuntu to the list of supported distributions. In fact it doesn’t end there, have a look at the complete list of Oracle provided images to see what’s (more...)

Terraforming the Oracle Cloud: choosing and using an image family

For a few times now I have presented about “cloud deployments done the cloud way”, sharing lessons learned in the changing world I find myself in. It’s a lot of fun and so far I have been far too busy to blog about things I learned by trial and error. Working with Terraform turned out to be a very good source for blog posts, I’ll put a few of these up in the hope of (more...)

opatch investigations

This blogpost is about opatch and how to obtain information about the current oracle home(s), and how to obtain information about the patches to be applied.

Patches that can be applied using opatch are provided by oracle as zip files which have the following naming convention:
p[patchnumber]_[baseversion]_[platform]-[architecture].zip. The patch normally contains an XML file called ‘PatchSearch.xml’ and a directory with the patch number. Inside the patch number directory there is a README.txt (more...)

Ansible tips’n’tricks: executing related tasks together

I have recently written an ansible playbook to apply one-off patches to an Oracle Home. While doing this, I hit a little snag that needed ironing out. Before continuing this post, it’s worth pointing out that I’m on:

$ ansible --version
ansible 2.6.5

And it’s Ansible on Fedora.

Most likely the wrong way to do this …

So after a little bit of coding my initial attempt looked similar to this:

$ cat  (more...)

creating local repository yum install linux

Follow the below procedure

[root@ebs-app-xx-xx u01]# yum repolist

[root@ebs-app-xx-xx u01]# yum list installed | grep createrepo

createrepo.noarch                         0.9.9-28.el7             @anaconda/7.5

[root@ebs-app-xx-xx u01]# createrepo /u01/Packages/

 

[root@ebs-app-xx-xx u01]# cd /etc/yum.repos.d

[root@ebs-app-xx-xx yum.repos.d]# ls -tlr

total 4

-rw-r–r–. 1 root root 358 Nov  4 22:55 redhat.repo

Now, create custom repository

[root@ebs-app-xx-xx yum.repos.d]# cat custom.repo

[customrepo]

name=Custom Repository

baseurl=file:///u01/Packages/

enabled=1

gpgcheck=0

 

you can check how (more...)

Oracle Database 18c: Installation via rpm (without runInstaller.sh)

Three months after writing the post Where to find the oracle-database-ee-18c-1.0-1.x86_64.rpm package? Oracle released the rpms on their download page:


https://www.oracle.com/technetwork/database/enterprise-edition/downloads/oracle18c-linux-180000-5022980.html

So let's give it a try.


First thing is to install the prerequisites:
# yum install oracle-database-preinstall-18c


...
=================================================================================================================================================
Package Arch Version Paketquelle Größe
=================================================================================================================================================
Installieren:
oracle-database-preinstall-18c x86_64 1.0-1.el7 ol7_latest 18 k
Als Abhängigkeiten installiert:
bc x86_64 1.06.95-13.el7 ol7_latest 114 k
bind-libs x86_64 32:9. (more...)

jconsole/visualvm/java applications without fonts over ssh forwarding (characters displayed as boxes)

On servers which run java applications sometimes you need to run jconsole or jvisualvm.
This is typically no problem - ssh -X and you are done.

But in some rare circumstances you will get something like this:


??

Following some other sources, you end up with tweaking xorg parameter without any success. The solution is very easy:
apt-get install ttf-dejavu
And then:


Oracle wait event ‘TCP Socket (KGAS)’

I was asked some time ago what the Oracle database event ‘TCP socket (KGAS)’ means. This blogpost is a deep dive into what this event times in Oracle database 12.1.0.2.180717.

This event is not normally seen, only when TCP connections are initiated from the database using packages like UTL_TCP, UTL_SMTP and the one used in this article, UTL_HTTP.

A very basic explanation is this event times the time that a database (more...)

Enable X11 on Oracle Cloud Infrastructure

Today my colleague was starting with the installation of Oracle Database on the Oracle Cloud Infrastrcture, for a customer. He phoned me for help on enabling VNC to have a graphical UI to install the database.

Install an ssh client with XServer emulator

Most of my co-workers of around my age, have grown up with Putty. And apparently we as computer consultants are quite hooked to our tools. I know, only yesterday I mentioned it (more...)