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Log Buffer #257, A Carnival of the Vanities for DBAs

With new year many new projects, new technologies, new frameworks and new ideas are springing up at the speed of light and bloggers in the database arena are keeping up with this pace and this Log Buffer Edition is also living up to that pace and covers some of those posts in Log Buffer #257.
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Log Buffer #256, A Carnival of the Vanities for DBAs

Searching for the blogging inspiration? On the look-out for that Eureka moment for your next blockbuster blog post? Finding the exact ingredients for your dream rambling? Well in the Log Buffer Edition, there are some awe-inspiring posts in this Log Buffer #256. Get Inspired, keep blogging.

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Log Buffer #255, A Carnival of the Vanities for DBAs

With winter and its cold weather starting to set in across most of the world, now is the time when travelers start to think about warming things up. For most, that means flying to hot and sunny destinations. Another way of looking at it, however, is to head out for a different kind of sizzle. There’s perhaps no better way to heat up the chilling months with blogging. Let’s snuggle up in this Log Buffer Edition with hot blog posts in Log Buffer #255.

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Log Buffer #254, A Carnival of the Vanities for DBAs

After having party and festive time during holidays, bloggers are returning with reinvigorated zest and with uplifted zeal and the blogs are sprouting energy and promise. The new year is already here and the blogs across the database rainbow are oozing colors of all kinds. This Log Buffer Edition depicts some of them in Log Buffer #254.

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Replication stopped with duplicate entry upon starting up of MySQL from cold backup

A few days ago, we faced a Duplicate entry problem in the mysqld server on one of our customer’s slave after cold backup. We do regular data sync checks for all of our customer’s as daily reports and check for data discrepancies between master and slave server’s, if any got picked up by our checks to investigate, and there was no issues for the particular server and with the report. When checked the entry details, there is a row with the same data in the table that was mentioned by Slave status Last_error entity.

Quick check on the error log showed that the slave was started after cold back’s and immediately stopped with a duplicate entry error and the mysqld server version is 5.0.77-log Source distribution. From the analysis of the below statements, we found that the slave SQL thread was stopped with the error at a position backwards than the SQL thread initialized after cold backup’s. Read the rest of this entry . . .

Log Buffer #253, A Carnival of the Vanities for DBAs

A very very Happy New Year 2012 to all of you. These are the festive and jubilant times when people look back on previous years and make plans for their new year and beyond. Well, this Log Buffer Edition is no different. This week covers the new year posts of the bloggers across the database arena in Log Buffer #253.

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Log Buffer #252, A Carnival of the Vanities for DBAs

As we all look forward eagerly to 2012, bloggers around the gblobe are writing about their insightful reflections on 2011. You’re also welcome to write your’s regarding to database arena in the comments, if you like. This Log Buffer Edition welcomes you to the new year with festive posts from Oracle, SQL Server and MySQL bloggers in Log Buffer #252.

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Log Buffer #251, A Carnival of the Vanities for DBAs

New Year is the time to bid farewell to the old year and welcome the coming year. It is the time to remember the golden olden blog posts. It is the time for new beginnings and new starts in life, and of course for new blog posts. Bloggers in the database arena are also enjoying the festivities with full zeal and zest and this Log Buffer Edition, which is Log Buffer #251 covers just that. Happy Holidays.

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Log Buffer #250, A Carnival of the Vanities for DBAs

Tis the season to be fearless in blogging and read the blogs around the database globe. To make your foray in intrepid world of database blogs, this Log Buffer Edition compiles some of the most interesting posts in this Log Buffer #250.

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Once again about innodb-concurrency-tickets

I had to refresh my knowledge on how InnoDB threads queue works the other day when debugging activity spikes on one of the customer’s production system and while I had general idea about InnoDB kernel and queue, thread concurrency and queue join delays I didn’t have a complete model of how InnoDB concurrency control works. This is what I knew before I started investigation:

  1. You can limit the number of threads that allowed to be executed inside InnoDB kernel with innodb-thread-concurrency
  2. If all slots in kernel are occupied other threads have to wait in the queue
  3. Thread will sleep for time specified by innodb-thread-sleep-delay before entering the queue

I also knew that there is variable innodb-concurrency-tickets and that it allows a thread to enter the InnoDB kernel several times before it has to wait in the queue again. But how actually it happens? Why would thread need to leave the kernel? Is it related to transactions that run multiple queries? This is something I didn’t know. Read the rest of this entry . . .

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