What Good are Tech User Groups?

Last week I met Ronan Miles of the powerhouse UK Oracle User Group (UKOUG). Just look at their event list. I put a simple questions to him: Why be part of a user group?

ORA-27123: unable to attach to shared memory segment


Of late, in one of our test unix (Sun Solaris) boxes, a database user is trying to connect to the database, but getting an error ORA-27123: unable to attach to shared memory segment” with permission denied issue.

Initially we thought that there might be an issue with SGA memory area or may be an issue with the shared memory segments and semaphores for the instance allocated. But later we found that the permission on ORACLE_HOME directory got changed accidentally with the full permission.

Here are our findings:

$ sqlplus testusr/password@testdb

SQL*Plus: Release (more...)


Outbound_connect_timeout comes into play when nodes in a cluster are down and we cannot wait for the OS timeout as this causes long delays in connect time. For example on Solaris the value of tcp_ip_abort_interval = 180000 ==> which is 180 seconds ==> 3 mins

In this post I will demonstrate how outbound_connect_timeout (OCT) can effectively avoid timeouts experienced by clients connecting to RAC nodes

If we take an example of the following connect string

(ADDRESS = (PROTOCOL = TCP)(HOST = sdby1-vip)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = sdby2-vip)(PORT (more...)

Missing Tables in Execution Plan

In Oracle 10g, one of the new features introduced for optimizer, named transformation. Using this features it may be possible that oracle internally removes some of the redundant tables those were involved only in join predicates.

To demonstrate the same following test case created –
1. Table with primary key.
2. Table with foreign key referencing the above created table.
3. Query that eliminates the primary key table and hence leads to faster execution.

SQL> create table pk_table (id number, name varchar2(20));

Table created.

SQL> alter table pk_table add constraint pk_id primary key(id);

Table altered.

SQL> create table fk_table (id (more...)

Review: uCertify PrepKit 1Z0-047

I was asked by uCertify to review their preparation kit product.

I am currently preparing myself for Oracle 1Z0-047 Oracle Database: SQL Certified Expert Exam and I thought this could be a good chance for me test my current knowledge and chose to review their preparation kit for exactly this (more...)

On a Mac everything “just works”? Think again!

Lured by the ads that the new Apple 24″ LED Cinema Display was “made for the Macbook Air”, I brought one home. But it is not made for my 4-month old MacBook Air – only for MacBook Air from November 2008 and later. Even though Apple needed another display connector (more...)

El query dinámico de los pobres

Luego de casi dos semanas sin postear, les presento un caso curioso que me ocurrió en estos días. Pues ocurre que como parte de una tarea de afinamiento de aplicaciones que me solicitó un cliente, encontré con ayuda de dbms_monitor y tkprof, que la sentencia responsable del problema de desempeño era una muy peculiar, se trataba de un query que siendo estático estaba escrito de tal forma que pretendía satisfacer varios criterios de búsqueda, (more...)

A Lesson and a New Goal for 2009

Just interviewed Mike Riley of the Oracle Development Tools User Group (ODTUG). He’s in town for the IOUC conference . He didn’t say this on tape, but in the car back to his hotel he said being a member of ODTUG makes him much better at his work and helps him (more...)

Cleaning up with ALL_TAB_COLS

| Jan 22, 2009
The way he barely lifted his feet off the ground when he walked, I could hear him approaching from the other end of the hall. I knew he was coming, and I dreaded it. I had just gotten off the phone with a former teammate who was moved to another department. They had a new database analyst who was struggling with his new "database independent" application, and he was sent my way. It was just

Follow me on twitter

I’ve started to twitter. In case you don’t know Twitter, it’s a communication service that can be used as a micro-blog – each post is 140 characters or less. Read more on the Wikipedia article on Twitter. You can sign up at http://twitter.com/ and follow me at http://twitter. (more...)

Save some disk space – One Reminder and a Cool Windows Command

CPU Reminder

It’s the time of the year when the January CPU is released. I’d like to remind you to think about cleaning up your obsolete backups from $ORACLE_HOME/.patch_storage directory (the ones that are not needed anymore for rollback purposes).

Starting from 10g R2 Oracle backs up the affected (more...)

Comic-Based Communication

These days, there are as many styles of documentation as there are of programming. Structured docs (waterfall model), topic-based writing (object-oriented development), less formal styles based around wikis (agile coding). Another one that I haven't seen given a name, is what I think of as comic-based communication.If you grew up with comic books, fingers poised next to "continued on 3rd page",

Goals for 2009

I just came across Seth Godin’s admonition on goal setting. I agree with him; goals are how we can make sure the work we do every day is taking us someplace we want to go. Upon quick reflection, my goals for 2009 as tech editor at Oracle:

1. Make my (more...)

ORA-12514 during switchover using Data Guard Broker

I’ve seen, on several occasions, questions being asked about data guard broker being unable to automatically start the databases during a switchover, failing with ORA-12514 - TNS:listener does not currently know of service requested in connect descriptor?

This is most likely because the special service db_unique_name_DGMGRL has not been registered (more...)

Oracle Portal success stories – only with BEA products?

The January edition of the Oracle Fusion Middleware Information InDepth newsletter has an article “Modern Portals Create Advantage in Uncertain Times“. Oracle quote two customer success stories (both banks) - interestingly, one of them is using Oracle WebCenter Interaction (which used to be BEA AquaLogic Interaction) and the other (more...)

¿Vas a aplicar un patch?, verifica posibles conflictos

De cuando en cuando nos topamos con algún problema que afecta el normal desempeño de la base de datos, o quizás de alguna aplicación, y luego de investigar llegamos a la conclusión de que es inevitable aplicar uno o varios patches, pero habrán notado que en el README.txt que acompaña a todo patch se indica:
"You must have NO OTHER PATCHES installed on your Oracle Server since the latest patch set"
Esta advertencia (more...)

You’ve Got to Fight for Your Invoker’s Rights

This post is about a PL/SQL feature that doesn't get enough respect, "invoker's rights".First off, what's its real name? Depending on the source, you'll see the feature name spelled "invoker's rights", "invokers' rights", or "invoker rights". That makes a difference -- you'll get different results in Google depending on what combination of singular, plural, and possessive you use. And to be

Using Quartz Scheduler on WebLogic Server

I'm not a Quartz expert but I keep on getting emails with Quartz questions as one of my blog was published as a featured article at TheServerSide.com 4-5 years back. I got some questions on using Quartz on WebLogic Server recently. I modified the original example to run on (more...)

HR lessons from Obama

President Elect Barack Obama takes over the President of US in a few days from now. While there are huge expectations, there is also a story of how wonderfully the whole campaign was driven
I came across this article in Harvard Business Publishing,Senator Obama has shown how powerful management innovation (more...)

How important is having Unix/Linux OS Knowledge for Oracle DBAs?


I wanna wish you all a very Happy New Year 2009 before being discussed on “How Important Having UNIX OS Knowledge for Oracle DBA?”

The main reason for discussing this topic is to encourage the novice or junior DBAs to have command on Unix/Linux Operating System as part of Database Administration. Because, when they were asked how comfortable they are working as DBA on Unix/Linux environment, then their responses are as following.

“They are pretty much comfortable working and administrating the databases on Windows Operating System as they were trained on administrating the database on Windows OS during (more...)