carlos's blog

Remote access using Oracle DBLINK


The easiest way to access from an Oracle database objects from another Oracle database is using a DBLINK (being the easiest does not mean that it is always the most desirable, the abuse of DBLINKS can create many problems, both of performance and safety)

To do this it's necessary a user with CREATE DATABASE LINK privilege, and create a DBLINK in the source database (A) by a simple statement such as:

Create database link LNK_from_A_to_B connect to USER identified by PASSWORD USING 'B'; 

'LNK_from_A_to_B' is the name of the link, 'USER' and 'PASSWORD' are the IDs of the user who will use the link to connect, which will inherit the permissions of all access through the link, and B is the name of the database's instance.

Using the DBLINK we can connect to the objects with the remote database's permissions that user has been provided in the creation statement.

To reference an object from the remote database should indicate the name of the object, concatenated with the character '@' and the name that we had given to the DBLINK.


select * from TABLA@LNK_from_A_to_B 

How to connect from Oracle SQL Developer with a remote SQL Server


The digital story of the Nativity


Great video showing through the use of social media an original story of Jesus' birth at Christmas.

Besides being fun, it's a good way to make a quick tour of the main features of Facebook, Twitter, YouTube, Google, Wikipedia, Google Maps, GMail, Foursquare or Amazon ...

How times change:)

A contest to send a DBA to space


Redgate has organized a contest for DBA's with a spectacular prize: A space trip!

The winner will be the first DBA to go into space. A very original initiative. If you want to apply, visit the page

If you take part, count with my vote 


This is the promotional video of DBA in space: 


Good luck!

Interesting resources and links about IBM Cognos


Documentación de IBM Cognos BIIn a Linkedin debate members have proposed a list of references and useful links about Cognos BI, as well as forums, blogs and resources. I've organized a bit the proposals. I hope you find it useful..

How to connect to a remote MySQL database



MySQL has some special features when making a connection from a remote client that if we do not know can complicate access to a MySQL database from a different machine that hosts the database.

With other databases such as Oracle or SQL Server, once that no firewall or anything like that prevents us from the client machine access to the server, using normally data acces from a database user we can 'enter'.

With MySQL, although access to the port, usually 3306, is open, the database can be configured to shut out external connections, and the result is the same as if the port was closed by a firewall:


telnet 3306
telnet: connect to address Connection refused
telnet: Unable to connect to remote host


If you get this result should consult the file /etc/my.cnf, and checking for bind-address variable or skip-networking.

If skip-networking is and is not discussed, edit the file and delete it, or make a comment to have no effect and allow external connections:


Open Data at Barcelona Web Congress


At the Web Congress in Barcelona, ​​I attended a workshop on Open Data in wich Martín Alvarez Espinar, W3C Spanish Office's head, and Jordi Graells i Costa, coordinator of content and innovation of the Generalitat de Catalunya, explained what is the international initiative Open Data, and how it is developed in concrete projects in some communities of Spain, as Asturias and Catalonia.

RHIPE: Using Hadoop to analyze very large data with R


Hadoop is an Apache project that provides an environment that supports the management of large amounts of data. Such systems are typically used to support the large amount of information generated by great social networks, especially when relational databases are beginning to have problems of scalability, or the cost of growth is too high.

Interesting resources from IBM Redbooks


IBM Redbooks

Interesting resources about DB2, Informix and IBM System X for BI from IBM Redbooks


Some MySQL news, tips and resources


News and interesting resources about MySQL announced on the last MySQL newsletter

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