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Displaying posts with tag: logs (reset)
What is the proper size of InnoDB logs?

In one of my previous posts, “How to resize InnoDB logs?”, I gave the advice on how to safely change the size of transaction logs. This time, I will explain why doing it may become necessary.

A brief introduction to InnoDB transaction logs

The transaction logs handle REDO logging, which means they keep the record of all recent modifications performed by queries in any InnoDB table. But they are a lot more than just an archive of transactions. The logs play important part in the process of handling writes. When a transaction commits, InnoDB synchronously makes a note of any changes into the log, while updating the actual table files happens asynchronously and may take place much later. Each log entry is assigned a Log Sequence Number – an incremental value that always uniquely identifies a change.

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Usability improvements in Tungsten Replicator 2.0.4

If you love a software product, you should try to improve it, and not be afraid of criticizing it. This principle has guided me with MySQL (where I have submitted many usability bugs, and discussed interface with developers for years), and it proves true for Tungsten Replicator as well. When I started working at Continuent, while I was impressed by the technology, I found the installation procedure and the product logs quite discouraging. I would almost say disturbing. Fortunately, my colleagues have agreed on my usability focus, and we can enjoy some tangible improvements. I have already mentioned the new installation procedure, which requires just one command to install a full master/slave cluster. I would like to show how you can use the new installer to deploy a multiple source …

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beware of the log

The MySQL general log is one of my favorite features for a quick debug. I especially like the ability of starting and stopping it on demand, which was introduced in MySQL 5.1.
However, using the general log has its drawbacks.
Today I was debugging a nasty bug that results from two statements that should be applied sequentially, but that were instead concurrent. These kind of problems are hard to cope with, as they are intermittent. Sometimes all goes well, and you get the expected result. And then, sometimes the statements fly on different directions and I stare at the screen, trying to understand where did they stray.
After some try-and-fail, I decided to enable the general log just before the offending statements, and to turn it down immediately after. Guess what? With the general log on, the test never failed. What was an intermittently …

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MySQL 5.4 performance with logging

About a month ago, I published the results of MySQL 5.x performance with logging. The results covered several versions, from 5.0.45 to 5.1.33. Among the conclusions of the post was the consideration that MySQL 5.0.x is faster than MySQL 5.1 in read only operations. I hinted that better results may come for MySQL 5.1. When I wrote that post I had, in fact, an ace up my sleeve, because I had already benchmarked the performance of MySQL 5.4, using the same criteria shown in my previous post. The results, as you can see from the charts below, tell that …
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MySQL 5.x performance with logging

There has been much talking about MySQL performance related to logging. Since MySQL 5.1.21, when Bug #30414 was reported (Slowdown (related to logging) in 5.1.21 vs. 5.1.20) I have been monitoring the performance of the server, both on 5.0 and 5.1.
Recently, I got a very powerful server, which makes these measurements meaningful.
Thus, I measured the performance of the server, using all publicly available sources, because I want this benchmark to be repeatable by everyone.
I will first describe the method used for the benchmarks, and then I report the results.The serverThe server is a Linux Red Hat Enterprise 5.2, running on a 8core processor, with 32 GB RAM and 1.5 TB storage.

$ cat /etc/redhat-release
Red Hat Enterprise Linux Server release 5.2 (Tikanga)

$ cat /proc/cpuinfo |grep "processor\|model name" | sort …
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Q&A on MySQL 5.1

Listening to Sheeri's presentation on MySQL 5.1, I saw that there are a few questions left unanswered. I am listing here some of the questions that I found interesting, plus a few from an early webinar on the same topic.

Q: does Partitioning physically split data?
A: No. Some engines (MyISAM, Archive) do a physical split, but this is not necessary, as you see if you apply partitioning to a InnoDB table. Partitioning is a logical split of data, for easy retrieval. It is completely transparent to the user.
Q: Can you set partitions to different servers?
A: No. Partitions are logical parts of one table within one server. Partitioning through the Federated engine is not supported.
Q: How efficient are Row-Based …
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New in MySQL 5.1: Sheeri’s Presentation

In a nutshell: What’s New in MySQL 5.1.

Release notes: Changes in release 5.1.x (Production).

And yes, very early on (at about two minutes in), I talk about my take on Monty’s controversial post at Oops, we did it again.

To play the video directly, go to To download the 146 Mb video to your computer for offline playback, go to The slides …

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MySQL 5.1.29 - Last RC - small changes

MySQL 5.1.29 is available.
This is the last RC. Yes. You heard me right. The long wait is almost over. The next release will be GA.
Sharpen your tools, and get ready to use partitions, row-based replication, and the event scheduler in production without that uneasy sense of guilt that you feel when using non-GA software.

There are a few small changes in MySQL 5.1.29.
SHOW PROFILESIt was already in a preview, but now SHOW PROFILES is available in 5.1 binaries. As you may recall, it is not active …

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