VirtualBox 5.0.18

VirtualBox 5.0.18 has been released.

The downloads and changelog are in the usual places.

So far I’ve only installed it on Windows 7, but I’ll no doubt be doing an install on OS X El Crapitan and Oracle Linux tonight. ūüôā



VirtualBox 5.0.18 was first posted on April 19, 2016 at 3:22 pm.
©2012 "The ORACLE-BASE Blog". Use of this feed is for personal non-commercial use only. If (more...)

Subtle variations in optimizer stats

Subtle variances in the way you work with statistics can have a significant impact on how your optimizer plans work out…so you need to take care.

Let’s look at the following example

SQL> create table T (
  2    x varchar2(20) , y varchar2(100));

Table created.

SQL> insert into T
  2  select 'x' , rpad('z',100) from all_objects;

94117 rows created.

SQL> insert into T
  2  select 'X' , rpad('z',100) from all_objects;

94117 rows created.

SQL> exec  (more...)

Monday night test

Here's an interesting little puzzle from today - I've distilled it into a simple demo - the basic problem that appeared can be summed up in the screenshot below

The two tables should have equivalent indexes - but the one index has SYS generated column names implying that something odd is going on.

Any guesses as to what it was (no reading ahead.....)?

Was it some weird NLS setting?

Was it some specially changed (more...)

OEL and Azure file shares

Of late I've been doing more and more stuff on Azure and have been considering setting up a separate blog on that - however I've decided this is all part of DBA 2.0 so i'll leave it all here. Even if you aren't sucked into the cloud yet it's useful to know this stuff as it's the way the whole IT world is going (be that for bad or good I'm still not sure).


java.lang nullpointerexception While Installing RAC Database Software

RSS content

I have an Oracle cluster having following 5 nodes :

  • Hub Nodes : host01, host02, host03
  • Leaf nodes: host04 and host05

I wanted to install RAC database software on the 3 hub nodes i.e. host01, host02 and host03.

I invoked the OUI as oracle user (Owner of Database Home)

[oracle@host01 database_12_1_0_2]$ ./runInstaller

and chose the option to install RAC database software only on the 3 hub nodes.

After (more...)

OTN Yathra 2016 ‚Äď OTN #OracleACE Conference Tour

Very happy and honored to speak in OTN Yathra 2016 tour, along with many Oracle ACE and ACE Directors. This is my first tour as ACED, and thank you AIOUG and OTN for having me. I am looking forward to meet many¬†of you, who I know only through twitter or facebook. I will be presenting […]

Quick tip on Function Based Indexes

For “normal” indexes, USER_IND_COLUMNS will contain the column name(s) for an index, but things (appear to) go astray when looking at function-based indexes.

SQL> create table blah ( x varchar2(30));

Table created.

SQL> create index blah_ix on blah ( upper(x));

Index created.

SQL> select column_name from user_ind_columns
  2  where index_name = 'BLAH_IX'
  3  /


Don’t panic. Simply take a look at USER_IND_EXPRESSIONS to find the function that you used.

SQL> select column_expression  (more...)

Video : Flashback Query

Today’s video is a quick demo of¬†flashback query.

If you prefer to read articles, rather than watch videos, you might be interested in these articles.

The cameo for this video comes courtesy of Dina Blaschczok, a DBA based in South Africa (more...)

A little known RI clause

Most people are aware of this standard referential integrity control, namely you can’t delete the parent if children exist

SQL> drop table PAR cascade constraints purge;

Table dropped.

SQL> create table PAR ( p int primary key, data int);

Table created.

SQL> insert into PAR
  2  select rownum, rownum
  3  from dual connect by level <= 7;

7 rows created.

SQL> drop table CHD purge;

Table dropped.

SQL> create table CHD ( c int  (more...)

%TYPE Declaration Gives PLS-00302

A developer reported a problem with a %TYPE declaration which was returning PLS-00302 in an Oracle 10 database. The cause turned out to be a variation on a problem which I have already reported. However, as it took me some time to work out, I have reproduced it below. First I created a user, called USER1, who would own a table:

SQL> conn / as sysdba
SQL> create user user1
  2  identified (more...)

Optimizer Stew ‚Äď Parsing the Ingredients to Control Execution Plans

No matter how many times I have worked with Outlines, Baselines and Profiles, I keep having to look up reminders as to the differences between these three.

There is seemingly no end to articles to the number of articles and blog that tell you what needs to be licensed, how to use them, and which version of Oracle where each made its debut appearance.

This blog will discuss none of that.  This brief article (more...)

Spot the Oracle Faces

My wife has been going through old photo’s from her mother today, trying to find a picture of Uncle Stan. In the box of photographs was also a magazine – an Oracle magazine!

Oracle Magazine award winners 2003!

Oracle Magazine award winners 2003!

As you can see, it is the front cover of Oracle Magazine from the end of 2003, with the Oracle Magazine 2003 Award Winners on it. The tiny photograph on the bottom right is me:-). Sue’s mum, (more...)

Wrong Results Involving INDEX FULL SCAN (MIN/MAX) in

One of my customers that recently upgraded to 12c hit a bug that I think is good to be aware of. Note that as the title of this post states, the problem only occur in At least, I wasn’t able to reproduce it in any other version.

To reproduce it you simply need a composite partitioned table with a non-partitioned or global-partitioned index. In other words, if all your indexes are (more...)

Hadoop performance troubleshooting with stack tracing, an introduction.

Topic: This post is about profiling and performance tuning of distributed workloads and in particular Hadoop applications. You will learn of a profiler application we have developed and how it has successfully been applied to tuning Sqoop to improve the throughput of data transfer from Oracle to Hadoop.


UKOUG RDBMS and RAC-CIA Special Interest Groups

On Thursday 21st April, there is a dual UKOUG Database and RAC, Cloud, Infrastructure and Availability special interest group.

For the first time, this even is being held in the fabulous Northern city of Manchester!

There are a dozen interesting, career-assisting, educational talks from end users, Oracle employees and a number of well known Oracle ACE’s at all levels, including Carl Dudley, Jonathan Lewis, Phil Brown and myself.

I will be talking about how (more...)

jq – a really useful unix utility

Hot on the heels of the last post is a quick note on JQ - thats not oracle job queues before you ask it's a unix utility that can parse json files and pull out individual elements - think of it as sed/awk for json files.

I've only scratched the surface with it today but though it worth sharing as it looks like it could be a very handy utility

installation is simple via this (more...)

Analyzing Performance

People ask me quite a lot about how I analyze performance issues. While I have some guidelines, there is no complete answer to this question. The actions I take depend on the situation, and there are many many different scenarios when talking about performance problems. In this post I’ll describe an analysis I did about […]

Azure command line on OEL

We're working more and more with azure related services at the moment and I've been looking in to the different ways that azure infrastructure can be created/managed other than through the web gui. The web gui is of course fine for basic tasks but we're looking at better ways of automating and reporting on what we have in Azure so have been looking at alternatives.

There are a number of ways to do this including:


New Installation Cookbook: Oracle Linux 6.7 with Oracle RAC

cookbookI’ve updated my install cookbooks page to include a new¬†cookbook for installation of¬†Oracle Real Application Clusters on Oracle Linux 6.7.

This is also the first one I’ve published since I left the employment of Violin Memory to work for Kaminario, so this install uses a¬†Kaminario K2 All Flash Array. However, it applies very well to any Oracle RAC installation which uses relatively capable¬†storage.


Filed (more...)

Active and Inactive Sessions

Most people are aware of the STATUS column in V$SESSION. If it’s ‘ACTIVE’ then that connection is in the process of consuming database resources (running a SQL statement etc).

However, a lesser known column which is probably even more useful is the LAST_CALL_ET column. The name suggests the time since the last call, but the documentation provides a more useful description:


If the session STATUS is currently ACTIVE, then the value represents the elapsed (more...)