CQRS through Twitter – more fun than meaning

As part of my 50 Shades of Data presentation, I talk about CQRS – Command Query Responsibility Segregation. The idea that you can have one or more read only data stores with data replicated from the master store where all data manipulation (commands) take place. In a different presentation, I introduce Apache Kafka and explain its concepts. In this article, these two topics come together, in a light hearted fashion.

My starting point is the (more...)

How to enable auto start/shutdown for Oracle Database 18c Express Edition

Oracle Database 18c Express Edition can be enabled for automatic startup and shutdown with the operating system. This will not only allow you not to worry about starting and stopping the database but it will also ensure that the database is properly shutdown before the machine is powered off. Enabling auto startup/shutdown is done via … Continue reading "How to enable auto start/shutdown for Oracle Database 18c Express Edition"

Oracle Gateway Installation for MSSQL Server on RHEL 7

Oracle Database Gateways

Oracle Database Gateways address the needs of disparate data access. In a heterogeneously distributed environment, Gateways make it possible to integrate with any number of non-Oracle systems from an Oracle application. They enable integration with data stores such as IBM DB2, Microsoft SQL Server and Excel, transaction managers like IBM CICS and message queuing systems like IBM WebSphere MQ.

Here Oracle gateways is installed to extract the data in the MSSQL SERVER (more...)

How to install Oracle Database 18c XE on Linux

The new version of the free Oracle Database edition, Oracle Database 18c Express Edition, just got released for Linux 64-bit. Getting started is really simple on Oracle Linux, basically a three step process of downloading the RPM file, installing it and then configuring the database. On other Red Hat  compatible Linux distributions you will also have … Continue reading "How to install Oracle Database 18c XE on Linux"

Oracle Database 18c Express Edition is Generally Available!

Oracle just released the new version of Oracle Database Express Edition (XE), a free edition of Oracle Database. This release means something special to me, as I have been closely involved in it and with the great team that brought us Oracle Database 18c XE. It has been 7 years since its predecessor, Oracle Database … Continue reading "Oracle Database 18c Express Edition is Generally Available!"

Recover From Redo Log File

This post explains about the steps are used by DBA for recovery From Redo Log File.

Check the archive log status

SQL> archive log list;
Database log mode              No Archive Mode
Automatic archival             Disabled
Archive destination            USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     2
Current log sequence              4

List the tablespaces

SQL> select name from v$tablespace;

SQL> select file_name from dba_data_files;

using AWR on Exadata

Oracle released a brand new Whitepaper for Exadata

How to use AWR Report on Exadata Machines

This Whitepaper gives details how the AWR reports can be used in conjunction with Exadata to monitor and analyze database performance issues





ORAchk (EXAchk) und der Collection Manager (Teil 2)

Nun geht es mit Teil 2 weiter.

Nach dem nun die APEX Installation fertig ist, geht es darum den Collection Manager zu installieren und zu konfigurieren.

Dazu empfehle ich sich für das Setup parallel die Dokumentation, also das User’s Guide „Oracle® ORAchk and EXAchk“ und hier Kapitel 1.9 Oracle Health Check Collections Manager for Oracle“ zu öffnen.

Wir melden uns nun am Admin Service an:



Der neue „Workspace“ wird erstellt. Im zweiten Schritt (more...)

ORAchk (EXAchk) und der Collection Manager (Teil 1)

ORAchk & EXAchk sind wichtige Tools im täglichen Oracle DBA Geschäft. Allerdings habe diese Tools wenn man Sie einmalig oder mehrfach startet den großen Nachteil das man jeweils einzelne Reports erhält und diese nicht miteinander vergleichen kann, oder eine Historie erhält. Es bedeutet im Umkehrschluss man muss sich selbst eine „Ordnung“ überlegen und die Verwaltung übernehmen.

Genau an diesem Punkt kommt nun der „Collection Manager“ ins Spiel, der eine komplette APEX Anwendung ist und die (more...)

DBMS_CLOUD Package – A Reference Guide

The Appendix A of the Using Oracle Autonomous Data Warehouse Cloud guide describes the DBMS_CLOUD package. Unfortunately, it documents only a subset of the subroutines. And, for some of them, the description could also be enhanced. Therefore, while I was testing all the subroutines the DBMS_CLOUD package provides, I took a number of notes. By the end of my tests, I got what I can call my personal reference guide to the package. Since it (more...)

Creating an Oracle Database Vagrant box

Oracle recently launched a new GitHub repository for providing people with Oracle software inside Vagrant boxes. If you have ever setup an Oracle database inside a VirtualBox VM, whether it is as your sandbox environment, to explore Oracle database, or to use it as a full-on development environment, things have just gotten a lot easier … Continue reading "Creating an Oracle Database Vagrant box"

Patch Recommendations for Oracle Database 12cR1 and Cloud Control 13cR2

During my consulting engagements I see a lot of systems and many bugs. Most of the time, there is already a patch available to avoid the bug. I have collected all the recommended patches for the Oracle Database (SE2 and EE) and Oracle Enterprise Manager 13cR2. This should help to avoid most critical known issues. Versions and 18c will be added later this year.

Patch Recommendations

BAAS: Battle Against Archiver Stuck – ALTERNATE Archive Location

If you are managing volatile systems, you might have encountered Archiver-Stuck in the past.

0RA-00257:archiver error, connect internal only until freed
ORA-16014:log 2 sequence# 1789 not archived, no available destinations

If this is the case, you might be interested in a rarely used feature called “ALTERNATE Archive Locations”. This is a second independent archive log destination, that is only used in case the primary destination is failing (full). In that case, the dest_2 is automatically (more...)

Modifications to hidden parameters between and

I recently troubleshooted an issue with RMAN catalog database using seperate schemas for each target database and more than 300 schemas present. Catalog Database was on and suffering from severe mutex contention because of huge version counts for RMAN catalog SQL statements. I then realized that the default number of max child cursors was increased from 1024 to 8192 in This made me check what other parameters (more...)

Oracle 18c – SQLPlus cute Features

As I got my fingers on the latest Oracle 18c Release, I had the chance to test some cute new features within SQLPlus, which are really helpful.


The new option WINDOW for SET LINESIZE automatically adjust your linesize to your current window size.

As you can see in the below screenshot, the first select was executed without the linesize option, so you will have the usual line break in your result set. (more...)


2 years ago, I have published an article series about the undocumented feature "ALTER USER RENAME":

As I was getting access to an Oracle 18c Database, I was trying directly, if the ALTER USER RENAME still works (more...)

Playing with 18c on Oracle Database Cloud Service – How to use and create a database STEP by STEP

  The Oracle Database Cloud Service (ODBCS)  is the DBaaS  extension of Virtual Image Service and includes additional automation for database provisioning during service creation, backup, recovery, and patching. While you are still responsible for the complete management of the environment,

Why I picked Postgres over Oracle, part III

This is the final episode of this short series of blog posts on some of my drivers for moving to Postgres from Oracle.
Please do read Part I and Part II of the series if you have not done so. It discussed the topics “History”, “More recently”, “The switch to Postgres”, “Realization”, “Pricing”, “Support” and “Extensibility”.

In summary:

  • Part one focused on “why not Oracle anymore, so much”
  • Part two discussed on the comparison (more...)

Why I picked Postgres over Oracle, part II

Continuing this short series of blog posts on some of my drivers for moving to Postgres from Oracle.
Please do read Part I of the series if you have not done so. It discussed the topics “History”, “More recently” and “The switch to Postgres”.


In the last months, discussing Postgres with my Oracle peers, playing with the software and the tooling, I actually quite quickly realized Postgres is a lot cooler, at least to (more...)

How Well a Query Optimizer Handles Subqueries?

At the beginning of December, at the UKOUG Tech17 conference in Birmingham (GB), I presented a comparison of the query optimizers of MySQL 8.0.3 and PostgreSQL 10.1. One of the things I talked about is their ability to handle subqueries. I summarized my findings with the following sentence:

Simple sub-queries that are not correctly optimized were observed.

It goes without saying that such a sentence leaves a lot of questions open. After (more...)