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Showing entries 1 to 12

Displaying posts with tag: logs (reset)

What’s the data on the 3Ci Data Team?
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3Ci processes over a billion transactions a month. More than 100 million unique U.S. consumers have engaged with a business through our platform. All that activity creates massive amounts of data. The Data Team at 3Ci is responsible for keeping our offerings running at optimal performance and for making sense of our data. They manage MySQL [...]   [Read more...]
What is the proper size of InnoDB logs?
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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

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Usability improvements in Tungsten Replicator 2.0.4
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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  [Read more...]
beware of the log
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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


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oak-hook-general-log: your poor man’s Query Analyzer
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The latest release of openark kit introduces oak-hook-general-log, a handy tool which allows for some analysis of executing queries.

Initially I just intended for the tool to be able to dump the general log to standard output, from any machine capable to connect to MySQL. Quick enough, I realized the power it brings.

With this tool, one can dump to standard output all queries using temporary tables; or using a specific index; or doing a full index scan; or just follow up on connections; or… For example, the following execution will only log queries which make for filesort:

oak-hook-general-log --user=root --host=localhost --password=123456
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EXPLAIN: missing db info
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I’m further developing a general log hook, which can stream queries from the general log.

A particular direction I’m taking is to filter queries by their type of actions. For example, the tool (oak-hook-general-log) can be instructed to only stream out those queries which involve creation of a temporary table; or those which cause for a filesort, or full index scan, etc.

This is done by evaluating of query execution plans on the fly. I suspect the MySQL query analyzer (http://www.mysql.com/why-mysql/white-papers/mysql_wp_queryanalyzer.php) roughly does the same (as a small part of what it does).

It’s almost nothing one cannot do with sed/awk. However, I bumped into a couple of problems:

  • The general log (and the
  •   [Read more...]
    oak-hook-general-log: streaming general log
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    I’m seeking input on a new openark kit utility I’ve started to implement.

    The tool, oak-hook-general-log, will hook up to a MySQL (>= 5.1) server, and stream the general log into standard output. It looks like this:

    bash$ python src/oak/oak-hook-general-log.py --socket=/tmp/mysql.sock --user=root
    2010-03-21 10:18:42     root[root] @ localhost []       79      1       Query   SELECT COUNT(*) FROM City
    2010-03-21 10:18:48     root[root] @ localhost []       79      1       Query   DELETE FROM City WHERE id=1000
    2010-03-21 10:18:54     root[root] @ localhost []       79      1       Query   SHOW PROCESSLIST
    2010-03-21 10:19:06     root[root] @ localhost []       79     
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    MySQL 5.4 performance with logging
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    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

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    MySQL 5.x performance with logging
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    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 server

    The 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)







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    Q&A on MySQL 5.1
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    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 Replication operations compared to Statement based

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    New in MySQL 5.1: Sheeri’s Presentation
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    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 http://technocation.org/node/663/play. To download the 146 Mb video to your computer for offline playback, go to http://technocation.org/node/663/download. The slides can be downloaded as a

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    MySQL 5.1.29 - Last RC - small changes
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    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 PROFILES

    It was already in a preview, but now SHOW PROFILES is available in 5.1 binaries. As







      [Read more...]
    Showing entries 1 to 12

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