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...)

Logging Triggers

Oracle Logging Trigger Results

This article demonstrates how you can write log files from triggers on different tables to the same logging table. This approach leverages Oracle’s object types and column substitutability features. It also eliminates the requirement to create a unique logging table for each logging trigger. The trick to accomplishing this requires mastering two skills.

The first skill requires you to learn how to create user-defined types (UDTs) and subtypes. The UDT stores (more...)

Critical Triggers

Oracle Critical and Non-critical Triggers

This article demonstrates how you can write critical and non-critical row-level triggers. You may ask yourself, what are critical and non-critical triggers? That’s a great question. A critical trigger stops processing and raises an exception within the scope of an Application Programming Interface (API). An API is typically a series of end-user forms that help you solve business problems. A non-critical trigger either allows users to perform undesired behavior or (more...)

Oracle Trigger Basics

Oracle Trigger Basics

Once you master the basics of inserting, updating, and deleting data from the database, you typically learn about database triggers. Database triggers are coding elements that let you manage events beyond the limit of database constraints.

Before you can appreciate the power of database triggers, you need to understand what database constraints can and can’t do. Then, together we’ll explore how you can implement database triggers.
Database constraints let you manage events. (more...)

Types & Column Substitutability

Object Types and Column Substitutability

This article shows you how to use extend parent (or superclass) objects. You extend parent classes when you implement specialized behaviors (or methods) in subtypes. That’s because SQL statements can’t work with specialized methods when a table’s column stores subclasses in a superclass column type.

Substitutability is the process of storing subtypes in a super type column. It is a powerful feature of the Oracle database. The “type evolution” feature (more...)

Types & Subtypes

Object Types and Subtypes

This article teaches you how to use subtypes or subclasses. You can define an object type with or without dependencies. Object types can have two types of dependencies. The simplest case occurs when you define an object attribute with an object type instead of a data type. The more complex case occurs when you define an object subtype because it inherits the behavior of the base object type. The base object (more...)

Type Getters & Setters

Object Types with Getters and Setters

This article is for you when you know the basics about how you work Oracle’s object types. It teaches you how to write effective getters, setters, comparators, and static methods. Please read my Object Types & Bodies Basic article if you’re not sure how to work with object types.

Getters access an object instance and return values from an instance variable. Along with getters, you have setters. Setters let (more...)

Type & Body Basics

Object Types and Bodies Basics

Oracle Database 10g gave us a new way to write PL/SQL – object types. Object types are different from standard PL/SQL functions, procedures, and packages. While you can pin packages in memory, object types go one step further. You can instantiate them, which means you can start them, assign values to their variables, and put them into your PGA’s memory. Object types provide you with new challenges writing programs (more...)

Preprocessing External Tables

A question that comes up now and again is there a way in Oracle Database 11g Express Edition to mimic some behavior in the Oracle Standard or Enterprise editions. Many of these questions arise because developers want to migrate a behavior they’ve implemented in Java to the Express Edition. Sometimes the answer is no but many times the answer is yes. The yes answers come with a how.

This article answers the question: “How (more...)

JSON, BLOB column and Check Constraint

Last week I attended Neil Chandler's session on JSON during the POUG conference in beautiful Sopot, Poland.
The JSON Developer's Guide recommends using BLOB for storing data, and this is what Neil also recommended.
I was under the (FALSE!) impression that it was not possible to put an IS JSON check constraint on a BLOB column, simply because I tried once and got an exception. After the session I asked Neil if this was (more...)

Oracle Database Backup Service Fails with: ORA-19511: – KBHS-00715: HTTP error occurred ‘oracle-error’ – ORA-29024

I discovered an Oracle Cloud Database Backup failing with:

Starting backup at 2018/09/08 20:00:04
current log archived
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of backup plus archivelog command at 09/08/2018 20:00:07
ORA-19554: error allocating device, device type: SBT_TAPE, device name:
ORA-27023: skgfqsbi: media manager protocol error
ORA-19511: non RMAN, but media manager or vendor specific failure, error text:
   KBHS-00715: HTTP error occurred 'oracle-error'
KBHS-00712: ORA-29024  (more...)

Index Monitoring in Oracle Database

Applies to ONLY Oracle Database 10gR1 through to 12cR1.
In Oracle Database 12cR2, this feature is replaced.  A new blog post of this feature will be posted in due course.

Since Oracle 10g, you can monitor indexes to see if they are being used or not.  Which is very useful as indexes, consume unnecessary CPU and I/O on DML activity if not used.  Therefore, it’s recommended to monitor indexes and any unused (more...)

Loading Tables with Oracle GoldenGate and REST APIs

With Oracle GoldenGate 12c (, you can now quickly load empty target tables with data from your source database. You could always do this in previous releases of Oracle GoldenGate, but the process has now been simplified using REST APIs and some scripting know-how. In this post, I’m going to show you, high level, how you can use the REST APIs and a bit of scripting to do an initial load (more...)

Adding a Datafile to Temp Tablespace

When monitoring Tablespace Usage (see my Tablespace Usage blog post for more info), there comes a point when you need to add a datafile to the temp tablespace to allow for growth and more importantly get below a monitoring threshold for example in OEM or OpsView.

Query to see Current Temp Datafiles State

To see the current state of the temp datafiles:

set pages 999
set lines 400
col FILE_NAME format a75
select d.TABLESPACE_NAME,  (more...)

Video: Oracle X$TRACE, Wait Event Internals and Background Process Communication

I have uploaded the the video of my Secret Hacking Session: Oracle X$TRACE, Wait Event Internals and Background Process Communication to my Oracle performance & troubleshooting Youtube channel.

The slides are in Slideshare.



NB! I am running one more Advanced Oracle Troubleshooting training in 2018! You can attend the live online training and can download personal video recordings too. The Part 1 starts on 29th January 2018 - sign up here!

ORA-00240: control file enqueue held for more than 120 seconds 12c

Occasionally, In Oracle 12c database, you may get ORA-00240: control file enqueue held for more than 120 seconds  error in the alert log file.

Well, as this error contains the word control file so it looks scary but if you are getting it infrequently and the instance stays up and running then there is no need to worry and this can be ignored as a fleeting glitch.

But if it starts happening too often and worst (more...)

Advanced Oracle Troubleshooting seminar in 2018!

A lot of people have asked me to do another run of my Advanced Oracle Troubleshooting training or at least get access to previous recordings – so I decided to geek out over the holiday period, update the material with latest stuff and run one more AOT class in 2018!

The online training will take place on 29 January – 2 February 2018 (Part 1) & 26 February – 2 March 2018 (Part 2).

The (more...)

Oracle Installer fails with [EXCEPTION]:java.lang.reflect.InvocationTargetException under RedHat 7.4

I recently had a customer with a fresh installed RedHat 7.4 system on which we wanted to install different Oracle Software in graphical mode, like Oracle Database, Oracle WebLogic Server and Oracle Data Integrator

Following error occured when we were starting the Oracle Installers, either runInstaller or java -jar fmw_12.

export JAVA_HOME=/u00/app/oracle/product/jdk1.8.0_131
export (more...)

Good old BIN_TO_NUM to check the overall status

A good while ago Chris Saxon, member of the AskTom answer team, asked on twitter which datatype you use when defining tables when you need a Boolean-representation. As you might know there is no Boolean datatype in SQL.
A lot of discussion followed which I'm not going to repeat.
Usually I use a VARCHAR2(1) with a check constraint for Y and N, but for a recent requirement I decided to use a NUMBER instead.