Shared database links

Shared database links are there since Oracle 9iR2, but strangely I have never seen their existence until a customer asked me how to identify in DBA_DB_LINKS (or ALL_) if a database link has been created shared or not…

First, shared database links aim is to reduce number of connection to remote database by sharing same connection link between source and remote by multiple users’ sessions. This can also be seen as a JDBC connections pooling to concentrate multiple session and limit number of real connections onto the database (to obviously save CPU and memory).

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Critical Patch Updates and Security Alerts

You surely receive such messages and most probably like me you trash them… No time to apply them, no support from applicative teams to test them on QA, tons of other things to do !

Example of January message:


Above message the first link redirect you to:

Then is you choose the latest one available you will be redirected to:

To finally go, for Oracle Database Oracle Database 11 g Release 2, version, to Note 1089044.1. In this note they mention what they call a Database Patch Set Update. A Patch Set Update (PSU) is a proactive, cumulative patch that contains the recommended bug fixes and the Critical Patch Update security content, and therefore is an option to apply instead of the Critical Patch Update (the taste of a patchset but not really a patchset, as it is changing only the last digit of your release).

As of September the 27th PSU for Oracle Database 11gR2 is available, this PSU obviously includes CPUJUL2010 BUT also contains lots of bugs correction.

So instead of applying one single one-off patch to correct a bug it could be interesting to apply the latest PSU to be more proactive. Please note that once you have decided to apply a PSU (that can be applied on any release) you cannot revert to CPU security update (in fact you can but it’s quite a lot of work).