Tag: DBA Lounge

What Makes a Good DBA?

A few days ago I had a new idea for a blog post. A post about what it really takes to be a good database administrator. I began by researching what others had done on the topic. At the end of this post you will find links to six of the posts I found that provided some insight into this question. Even after uncovering this information, I thought I could add something to the mix from my own experiences. So here we go!

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Liberty Medal Awarded to Gorbachev

Interesting results you can see from some low quality news aggregators Looking at this page you might think that I’m awarded with the Liberty Medal. I’ve got this link while browsing the search results for RAC Attack. I guess should ask my granddad to pass my best wishes to Mr. George H.W. Bush.

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How Do You Edit a dump/exp/script File?

If you work with databases long enough, you run into a certain problem. You have a mysqldump file* of a table or a database, and you need to import it into your new database. However, you need to change something in the file first. Well, one simple solution is to use the sed tool to modify the file. Sed actually stands for “stream editor”. The vi editor would be considered a static editor in that it loads all of the file into memory at once. If you run out of memory, you are out of luck.

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Tuning Latch Contention: Cache-buffers-chain latches

Recently, I had an opportunity to tune latch contention for cache buffers chain (CBC) latches. The problem was high CPU-usage combined with poor application performance. A quick review of the statspack report for 15 minutes showed a latch-free wait as the top event, consuming approximately 3600 seconds in an 8-CPU server. CPU usage was quite high. First, I’ll find the SQL suffering from latch contention and objects associated with the access plan for that SQL. Next,I will find the buffers involved in latch contention, and map that back to objects. Finally, I will match these two techniques to pinpoint the root cause.

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MS Windows Vista Tips for Administrators

I found myself, as a fresh member of The Pythian Group, losing precious moments just to change a few standard administrative settings on my new laptop with Microsoft Windows Vista. Having found the answers, I’m sharing them with you so that you can save some time, or spend it more pleasurably out in the summer.

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Bug in DBD::Oracle’s execute_array with 11g

There seems to be a bug in DBD::Oracle’s execute_array when working with 11g. If you tell DBD::Oracle to autocommit, it seems that in 11g this commit will not take place when an error occurs during the processing of one of the tuples that you passed into execute_array. I included the tables, code and workaround in this post.

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Falcon Transactional Characteristics

It’s time to continue our series on the transactional storage engines for MySQL. Some might question why I even include Falcon because it is very much beta at this time. MySQL, however, has made quite an investment into Falcon, and while it is currently beta, the code is improving and it looks like that it will be production-worthy when MySQL server 6.0 hits GA. I am going to concentrate quite a bit on the Falcon/InnoDB comparison as that is what everyone wants to talk about. This is despite my having heard MySQL employees repeatedly make statements to the effect of, “Falcon is not going to replace InnoDB,” or “Falcon is not competing with InnoDB.” Well, take that with a grain of salt. It certainly seems to me that they are competing for the same spot.

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Oracle Apps 11.5.9: Post-Clone Fails if DBA_JOBS Not Turned Off

We recently had an issue with a client while cloning a huge database. The result was that we had to restore the whole database as the post-clone corrupted the existing database. Pain! It took another fourteen hours to restore. This may help you to troubleshoot the issue.

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dbWatch News

Seems I have turned into a bit of a news source. dbWatch Software sent me a news release on their dbWatch monitoring platform, which looks like it might be an interesting product for those who work in a heterogeneous database environment. Here’s the release.

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InnoDB Transactional Characteristics

InnoDB is a storage engine that uses MVCC (described shortly) to provide ACID-compliant transactional data storage using row-level locking. MVCC stands for Multi-Version Concurrency Control. It is how InnoDB allows multiple transactions to look at a data set of one or more tables and have a consistent view of the data. MVCC keeps a virtual snapshot of the dataset for each transaction. An example will make this clear.

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