Dead Connection Detection (DCD) and the Oracle database

Dead Connection Detection is a useful feature of the Oracle database: it allows for the cleanup of “dead” sessions so they don’t linger around consuming memory and other system resources. The idea is simple: if the database detects that a client process is no longer connected to its server process, it cleans up. This can happen in many ways, in most cases this kind of problem is triggered by an end user.

A dead connection (more...)

UKOUG 2019

At the UKOUG TechFest 2019 event in Brighton this year I’ll be chairing the CBO Panel session on Monday 2nd December at noon. The panellists will be Maria Colgan, Nigel Bayliss, Christian Antognini and Richard Foote.

It will be possible to propose questions on the day – written or spoken, but this if you have a question that you’d like to give the panellists a little warning about then you can:

Presenting at UKOUG Techfest19 Conference in Brighton, UK

I’m very excited to be attending my 3rd UKOUG Conference, this year re-badged as Techfest19. The fact it’s being held in Brighton is a little disconcerting for a Crystal Palace fan, but really looking forward nonetheless to what has always been one of the very best Oracle conferences on the yearly calendar. I have a […]

OEM SSL Cipher Hardening Reset After Securing OMS

I have recently been installing Oracle Enterprise Manager at several sites, and one of the key requirements has been to ensure that the installation isn’t using insecure HTTPS protocols. Securing the OMS and agents typically consists of two components – ensuring that only secure SSL ciphers are being used, and shutting down protocols that have known vulnerabilities. Thankfully, Oracle has documented the procedures in two separate MOS notes:

Doc ID 2138391.1 – 13c: How (more...)

Estimating how much write I/O is not logged

I am trying to figure out how much non-logged write I/O an Oracle database is doing. I want to run an ALTER DATABASE FORCE LOGGING command on the database so that I can use Oracle GoldenGate(GGS) which reads updates from Oracle’s logs. GGS will miss writes that are not logged. But if I turn on force logging it may slow down applications that depend on non-logged writes for good performance. So, I want to (more...)

Announcement: Australia/NZ “Let’s Talk Database” Events October 2019 !!

I’ve very excited to announce the next series of Oracle “Let’s Talk Database” events to be run throughout Australia and New Zealand in October 2019. I’ll be discussing two exciting topics this series, “Oracle Database 19c New Features” and “Oracle Exadata X8“. As always, these sessions run between 9am-1pm, include a networking lunch and are free, […]

#CodeOne Session: Let’s Talk AI, ML & DL

Date: Tuesday, 2019-Sep-17 6:00 PMLocation: Moscone South – Room 202 Session: DEV2161 Abstract: You hear everywhere that your job will be taken over by machines and that you need to be doing something else to be relevant. If the job involves making a decision based on a pattern or data analysis (radiology, for example), you …

#OOW19 Session: It’s all in the presentation of data!

Date: Tuesday, 2019-SEP-17 11:15 AMLocation: Moscone West – Room 3020A Room Setup: OPEN AIR – AUDIENCE HEADSETSSession: CON2173 Abstract:DBAs usually collect a lot of data and present it in a tabular format, but management and users like and understand visual representation of data better. The tabular format does not make the impact or get the …

Oracle Database 19c Automatic Indexing: Default Index Column Order Part II (Future Legend)

In Part I, we explored some options that Oracle might adopt when ordering the columns within an Automatic Index by default, in the absence of other factors where there is only the one SQL statement to be concerned with. A point worth making is that if all columns of an index are specified within an […]

Jami (Gnu Ring) review

An unavoidable fact of database support life is webconferences with clients or users. Most of the time, we’re more interested in what’s going on onscreen than in each others’ faces. But every now and then we need to have a face-to-face. Skype is popular, but I recently had the chance to try out a FOSS alternative with better security: Jami.

Jami (formerly Gnu Ring) is a FOSS alternative to Skype that advertises a great featureset (more...)

Amazon QLDB and the Missing Command Line Client

Amazon Quantum Ledger Database is is a fully managed ledger database which tracks all changes of user data and maintains a verifiable history of changes over time. It was announced at AWS re:Invent 2018 and now available in five AWS regions: US East (N. Virginia), US East (Ohio), US West (Oregon), Europe (Ireland), and Asia Pacific (Tokyo).

You may ask why you would like to use QLDB (a ledger database) instead of using your traditional (more...)

Update restarts

Somewhere I think I’ve published a note about an anomaly that’s been bugging me since at least Oracle 10g – but if it is somewhere on the Internet it’s hiding itself very well and I can’t find it, though I have managed to find a few scripts on my laptop that make a casual reference to the side effects of the provlem. Anyway, I’ve decided to create some new code and write the article (all (more...)

Vagrant Build of AWX on Oracle Linux 7 Using Docker-Compose Method

I may need to do a bunch of scripting related to our load balancers, and I have the choice of using the API from the servers directly, Ansible Core or the web services exposed by AWX. I wanted to play around with AWX anyway, so that seemed like a good excuse…

First step was to install AWX. It’s pretty easy, but I must admit to spending a few minutes in a state of confusion until (more...)

Azure Advisor And Fixing Errors

Azure can be configured to send you advisor reports detailing things that are not quite right in your environment. The advisor is not necessarily always right but it’s sensible to review the outputs periodically, even if they relate to non production environments.

A few issues popped up on an advisor report on my recent travels and although you can just use the entries on the report on the portal to target the offending resources, I (more...)

Oracle GoldenGate Microservices Upgrade – 12.3.0.x/18.1.0.x to

Oracle GoldenGate Microservices have been out for a few years now. Many customers have pursued the architecture in many different industries and have this in many dfifernt use-cases and architectures. But what do you do when you want to upgrade your Oracle GoldenGate Microservices Architecture?

In a previous post, I wrote about how to upgrade Oracle GoldenGate Microservices using the GUI or HTML5 approach in this post – Upgrading GoldenGate Microservices Architecture – GUI Based (more...)

Quiz Night

Upgrades cause surprises – here’s a pair of results from a model that I constructed more than 15 years ago, and ran today on 12.2, then modified and ran again, then ran on, then on It’s very simple, I just create a table, gather stats, then update every row.

rem     Script:         update_nochange.sql
rem     Author:         Jonathan Lewis
rem     Dated:          Sep 2019
rem     Last tested 

Finding databases on each SQL Server using Powershell

A client had the requirement to list out the SQL Servers and the databases they have installed on those SQL Servers in their Azure Cloud environment this week. The reason for the requirement was to find SQL Servers that no longer had any databases on them so they could be considered for removal.

Essentially, it gathers a list of SQL Server resources, loops through them and counts and itemises them, not including the master database (more...)

Speaker info for Perth, Australia

I have just got back from the Groundbreakers Latin America tour, and the travelling was made so much easier with the information provided by the organizers. So with the APAC tour coming up, I felt duty bound to give some hopefully useful information about my home town in Perth.

Flying in/out

There are two airport terminals in Perth. In times gone by, these were known as the Domestic and International terminals because, as the names (more...)

Oracle OpenWorld and Code One 2019

It’s nearly time for the madness to start again. This will be my 14th trip to San Francisco for OpenWorld, and however many it is since Java One and Code One got wrapped up into this…

  • Flights booked : ✔
  • Hotel booked : ✔
  • ESTA approved : ✔
  • Irrational fear of flying and general anxiety : ✔
  • 80 lbs weight loss : ❌
  • Talk complete : ❌
  • Denial : ✔

At the moment the scheduled stuff looks like this.

Friday :


I saw a couple of messages like this in an Oracle listener log recently:

TNS-01189: The listener could not authenticate the user
I knew that somebody in another country was carrying out internal security scans and suspected this may have been the reason. To confirm, I tried to check the status of the listener from another server and was able to reproduce the error as follows:
UNIX: lsnrctl status 10.80.1. (more...)