Oracle 12c RAC on Oracle Linux 7 using VirtualBox

virtualbox I’m a little late to the party here, but I’ve finally got round to updating the VirtualBox 12c RAC article for Oracle Linux 7.

It’s not hard to do these VirtualBox RAC installations, but I find the process of putting the articles together really tedious. There are so many screenshots. That’s why it’s taken a while to build up the motivation to (more...)

Site Maintenance (20th Sept 2015 22:00 GMT) : Update

DiagnosticsLast night was the big server move. According to my monitoring, the site went down at approximately 23:30 GMT last night and was back again by 01:30 GMT this morning, so the site was offline for about 2 hours.

Everything looks normal to me this morning, so it I guess the move of my server between the racks in their data centre went OK. :)



Site Maintenance (20th Sept 2015 22:00 GMT) : Update was (more...)

Automation for DBA – Vagrant part 2


In the last post I presented steps to create Virtual Machine using Vagrant with Virtual Box. It is a native combination but there are other possibilities as well. This post will cover an integration of Vagrant tool with KVM hypervisor and AWS EC2 cloud.

In both cases, an additional plugins has to be installed:
-    vagrant-libvirt plugin for KVM -
-    vagrant-aws plugin for EC2 -

If there is a (more...)

Site Maintenance (20th Sept 2015 22:00 GMT)

DiagnosticsJust a quick heads-up about some work going on tomorrow on the website.

My hosting provider has decided my server needs to be put into a new rack, so somewhere after 22:00 GMT tomorrow (20th Sept 2015) the server will be switched off, moved to a new rack and switched on. They say the process should be complete within 4 hours. I’m hoping this is a massive overestimate. :)

If you are trying to use the (more...)

ORA-01917: user or role ‘PDB_DBA’ does not exist

I manually created a container database (CDB) in my Linux 6.4 based virutal machine. After creating it, I tried to create a pluggable database but got following error:

SQL> select instance_name,status from v$instance;

---------------- ------------
cdbtest          OPEN

1 row selected.

SQL> show con_name


SQL> select * from cdb_pdbs;

      DBID    CON_UID GUID                             STATUS    CREATION_SCN
---------- ---------- -------------------------------- --------- ------------

Log Buffer #441: A Carnival of the Vanities for DBAs

This Log Buffer Edition dives deep into the ocean of blogosphere and surfaces with some cool blog posts from Oracle, SQL Server and MySQL.


  • Lets Talk DB Perth
  • The Fundamental Challenge of Computer System Performance
  • Index Advanced Compression: Multi-Column Index
  • Middleware Diagnostics Advisor (MDA) Setup
  • Most people are now aware that in 12c, a VARCHAR2 has been extended from a maximum size of 4000 to 32767 bytes.

SQL Server:

The Issue of Exceptions in your Mailing Lists

A couple of days ago I got the below email about the next UKOUG Database Server SIG being full. That’s great to see! A full user group meeting. If I still wanted to attend, I could be added to the waiting list:

ScreenHunter_42 Sep. 14 11.25

It made me smile as, guess what, I was already due to be there. I was the last speaker on the agenda! It was going to be awkward if I failed to get (more...)

Switch off database network ACL’s

This is a reminder for me as much as anything - the damn acl's that control what traffic can be allowed from 'inside' the database are a real pain and sometimes its nice just to switch the things off - here is the code block to do that

 acl =>         'norules.xml',
 description => 'everything allowed',
 principal =>   'PUBLIC',
 is_grant =>    true,
 privilege =>   'connect'

Exadata X5 PDU – CLI already in use

Exadata X5-2 and X4-8B racks are delivered with the “Enhanced” PDU metering units connected via the Cisco switch. Although the documentation says they should have static addresses, they don’t. You need to configure them manually using serial console connection, this is described in my earlier post here.

However if you forget to exit the serial console connection to the PDU and then try to login using SSH later you’ll get the following message:

login as:  (more...)

SANGAM15 – See you there!

I mentioned my Oracle OpenWorld 2015 trip in a previous post. Yesterday evening I picked up my passport with my lovely new India visa in it!

The talks are written. The flights are booked. The hotel is booked. I have a visa. So that’s me sorted for SANGAM15 in November! :)

It’s going to be a rather hectic few days. I fly out, do the 2 day conference, then fly straight home. It looks like I (more...)

Row transposition

Here’s a couple of simple examples to get you started with transposing rows to columns. The problem typically presents as:

How do you convert a listing in rows (eg, where people placed in a race), into some output that is across the page ?

For example, given a running race, how do you generate output which looks like this:


So here’s our source table

SQL>  (more...)

BI Publisher Tips and Techniques

A colleague of mine asked recently if we had any <evil term alert>best practices</evil term alert> for BI Publisher, the latest and greatest reporting tool we use within Enterprise Manager (the old tool, Information Publisher, is of course also still supported but this post is relevant to BI Publisher). As you would well know if you’ve been following my posts or heard me presenting at conferences, <evil term alert>best practices</evil term alert> is a term (more...)

We are hiring!

Gluent – where I’m a cofounder & CEO – is hiring awesome developers and (big data) infrastructure specialists in US and UK!

We are still in stealth mode, so won’t be detailing publicly what exactly we are doing ;-)

However, it is evident that the modern data platforms (for example Hadoop) with their scalability, affordability-at-scale and freedom to use many different processing engines on open data formats are turning enterprise IT upside down.

This shift has already been going (more...)

The Fundamental Challenge of Computer System Performance

The fundamental challenge of computer system performance is for your system to have enough power to handle the work you ask it to do. It sounds really simple, but helping people meet this challenge has been the point of my whole career. It has kept me busy for 26 years, and there’s no end in sight.

Capacity and Workload

Our challenge is the relationship between a computer’s capacity and its workload. I think of capacity as (more...)

Index Advanced Compression: Multi-Column Index Part I (There There)

I’ve discussed Index Advanced Compression here a number of times previously. It’s the really cool additional capability introduced to the Advanced Compression Option with, that not only makes compressing indexes a much easier exercise but also enables indexes to be compressed more effectively than previously possible. Thought I might look at a multi-column index to highlight just […]


I was asked to run some SQL today and it generated an ORA-01440. I did not remember having seen this error before so I decided to check it out in an Oracle 11.2 database. First I created a table and added a row of data to it:

SQL> create table tab1(col1 number)
  2  /
Table created.
SQL> insert into tab1 values(1)
 2  /
1 row created.

Then I (more...)

Forcing OEM Target Detail Discovery

The Problem – Missing Target Details

I was evaluating an Information Publisher report containing data about host targets. The report is based on the sysman.mgmt$os_hw_summary view that contains all sorts of information about your hosts.  It is an excellent data source for Information Publisher reports.  Unless the data is missing.

One of my hosts didn’t appear in that view, even though the host’s console page appeared healthy.  Then I looked at the details.  Instead (more...)

Optimizer statistics – parse time statistics aggregation

It’s getting harder and harder to find time for writing. Anyway, this post stays from a long time in my draft so, I think is time to finish and post it. That one is the last one from the optimizer statistics series. For now, of course :) After describing the horror around the way that […]

Part 3: Comparing Oracle Cloud Database Backups Options

Comparing Oracle Database Backup Service (ODBS) and Oracle Secure Backups (OSB) to Amazon Web Services (AWS)

This is part 3 of a 3 part series on “Getting Started with Oracle Cloud Backups”.

  • Part 1 covers setting up RMAN to backup directly to the new Oracle Cloud Database Backup Service (ODBS).
  • Part 2 covers setting up RMAN to backup directly to the cloud using Amazon Web Services (AWS) Simple Storage Service (S3).
  • Part 3 compares and (more...)

Part 2: Oracle Cloud Backups to AWS S3

Getting Started with Oracle Cloud Backups – Amazon Web Services (AWS)

This is part 2 of a 3 part series on “Getting Started with Oracle Cloud Backups”.

  • Part 1 covers setting up RMAN to backup directly to the new Oracle Cloud Database Backup Service (ODBS).
  • Part 2 covers setting up RMAN to backup directly to the cloud using Amazon Web Services (AWS) Simple Storage Service (S3).
  • Part 3 compares and contrasts the two services.