Tag: DBA Lounge

Undocumented parameter _fix_control: How to break your database

Beware this parameter can prevent your database from starting. Indeed it can prevent your instance from starting! There are two dynamic views v$system_fix_control and v$session_fix_control which were introduced in 10.2 and control whether fixes for bugs in the optimizer can be turned on or off. This can also be controlled using the _fix_control initialization parameter. Also beware if setting this parameter in a running database. You can prevent further logins if you get it wrong or indeed try to unset it. Do not do. The moral of the story is be very careful with undocumented parameters when upgrading!

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Oracle RAC, v$, and gv$

I have experienced some pain at the hands of the Oracle RAC. My first encounter was about five months ago when I first became an “official” DBA. Being eager to jump into solving problems in my new job (as that’s what most DBAs do, solve problems), I relished the chance to get my hands dirty and work on a “real” DBA task — a database lock. Checking with a few knowledgeable co-workers, I was directed to a set of common database diagnostic scripts affectionately known as the “Pythian Kit”. his wasn’t the confidence-boosting exercise that I had anticipated.

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When SHOW SLAVE STATUS and the error log Disagree

When I do a show slave status\G, sometimes mysqld will lie to me and give me a wrong Exec_Master_Log_Pos. Let me explain with a situation from last night. In summary, the slave SQL thread is stuck (in this case because of a problem during the transfer of the binlog data to the slave’s relay log). The show slave status\G command tells me that it is stuck at the master binlog file mysql-bin.000480, position 126.

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Don’t Assume Anything

I’ll preface this post with a note that the story itself is not really work- or DBA-related, but the lessons learned certainly are. I consider myself fairly conscientious when it comes to internet security and backing up my most important files (pictures of kids, music, etc), and I am diligent about taking at least a weekly backup of those files so that if (when) something catastrophic happens, I am ready. Once again, as my short life as a DBA has proven, theory and practicality rarely meet.

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A Question from OTN Forum

Here is the question that was posted on OTN Forum Grid Control Extensibility. My first reaction was — how stupid one should be to post such absolutely irrelevant question in that forum? I was even more surprised that someone actually tried to provide a sensible response…

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DBD::Oracle and Instant Client 11.1.0.6.0

I have just managed to get DBD::Oracle to successfully compile, install, and test with the 11.1.0.6.0 Instant Client (IC) on a Linux (32bit) OS. It seems Oracle, in its wisdom, has changed the folder structure yet again, so to get it to compile, try this….

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SQLTeach Toronto: Almost Here

Toronto SQLTeach conference is now only a few weeks away. This conference includes quite a few interesting SQL Server-related sessions, on topics ranging from best practices, to performance, to some of the new SQL Server 2008 features.

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11i Forms Load-Balancing Using JServ

I ran into an 11i E-Business Suite instance which is using Apache/JServ to do forms load-balancing. Here is quick sketch of the instance architecture, a brief overview on how forms load-balancing happens in above architecture, and me more technical details — basically, the XML tags in the Context XML file in APPL_TOP that need to be edited.

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DBD::Oracle 1.21 Released

The latest release of DBD::Oracle is now ready and can be found at: CPAN DBD::Oracle. It is a Perl module that works with the DBI module to provide access to Oracle databases. The release has been fully tested with the latest version of DBI (1.601). I also included a list of the changes and/or fixes in this release.

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MySQL Plug-in 0.42 for Oracle Grid Control: First Beta Released

has finally happened! The first public release of the MySQL plug-in for Oracle Enterprise Manager 10g Grid Control is out. In the last few months, more and more people showed interest in the potential plug-in, and even few guys from Oracle contacted me independently of each other with their own reasons to have a MySQL plug-in available. This interest accelerated the fermentation of thoughts in my brain, and I got down to work. Pythian generously sponsored my development time. Here are the details. The first release version is 0.42 because that’s obviously the perfect number to start something good.

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