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10 Newer Entries Showing entries 61 to 70 of 110 10 Older Entries

Displaying posts with tag: bugs (reset)

How MySQL Workbench breaks itself
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Once upon a time, there was a policy in MySQL not to add new features after the beta stage.
To my surprise, MySQL Workbench 5.2.30 introduces a new feature, the query formatter. I gave it a try. The results are not extremely encouraging. Granted, it's a plugin and not a feature in the core application, but nonetheless one would expect something more stable in a GA release, especially since the plugin features are displayed in the main menu, and unless you have read the announcement, you couldn't easily tell the core from the …

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Warnings are now actual problems
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Yesterday, I reached a happy milestone in HailDB development. All compiler warnings left in the api/ directory (the public interface to the database engine) are now either probable/possible bugs (that we need to look at closely) or are warnings due to unfinished code (that we should finish).

There’s still a bunch of compiler warnings that we’ve inherited (HailDB compiles with lots of warnings enabled) that we have to get through, but a lot will wait until after we update the core to be based on InnoDB 1.1.

Federated tables bug
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Scenario
Recently came across this bug when trying out the federated storage engine for the first time in MySQL 5.1. Had a security table with user information on a remote server & database that needed to be joined to a local table housing site-specific permissions but only containing user IDs. I definitely wanted to use the “create server” method for the new table in case we later decided to link to a different table in the same remote database. A terrific little feature of the MySQL federated storage engine, to be sure.

Problem
The local …


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Two subtle bugs in OUTER JOIN queries
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OUTER JOIN queries in SQL are susceptible to two very subtle bugs that I’ve observed a number of times in the real world. Daniel and I have been hammering out ways to automatically detect queries that suffer from these bugs, in a relatively new Maatkit tool called mk-query-advisor. It’s part of our series of advisor tools for MySQL. I wrote a blog post about it a while ago. Automated analysis of bad query patterns is a good thing to write tools to do, because …

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Joining on range? Wrong!
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The problem I am going to describe is likely to be around since the very beginning of MySQL, however unless you carefully analyse and profile your queries, it might easily go unnoticed. I used it as one of the examples in our talk given at phpDay.it conference last week to demonstrate some pitfalls one may hit when designing schemas and queries, but then I thought it could be a good idea to publish this on the blog as well.

To demonstrate the issue let’s use a typical example – a sales query. Our data is a tiny store directory consisting of three very simple tables:

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mysql_upgrade and Innodb Tables
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Upgrading from MySQL 5.0 to MySQL 5.1 or Percona Server 5.1 you may run into issues with mysql_upgrade - it will identify some tables to be upgraded and will attempt to run REPAIR TABLE for them. This will fail with "The storage engine for the table doesn't support repair" error message. This seems to confuse a lot of people and I've seen people doing failsafe upgrade path of dumping and reloading complete database confused by this error message, which of course works, but can take quite a lot of time.

Another solution is to simply run ALTER TABLE tbl ENGINE=INNODB which will rebuild table with new MySQL …

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The Linux Bloke chuckles that Linux runs some Windows software (including Windows itself!) better than Windows does!!!
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Our Universe is full of ironies. But some ironies are just too hard to take.

As you may have guessed (!!!), I am an avid Linux developer and user. Though once upon a time I did develop under Windows. Yes, believe it. And on one particular case, I got to be on a first-name basis with some of the Microsoft Software Engineers to resolve issues we were having with their OLE crap — what the Holy Gods of Microsoft decided to redub as “Active-X”.

But I digress. For the past 10 years, I have been solid Linux and have defenestrated Windows for the most part. But as you know, you can never really completely eliminate Windows.  Despite your best efforts, it …


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Two quick performance tips with MySQL 5.1 partitions
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While I was researching for my partitions tutorial, I came across two hidden problems, which may happen often, but are somehow difficult to detect and even more difficult to fix, unless you know what's going on, and why. I presented both cases during my tutorial, but there were no pictures to convey the mechanics of the problem. Here is the full story.

TO_DAYS() prunes two partitions instead of one
If you are partitioning by date, chances are that you are using …


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The MySQL documentation is not always right
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Let me premise this post with the statement I think the MySQL documentation is an excellent and highly accurate resource. I think the MySQL docs team do a great job, however like software and people, documentation is not perfect.

As members of the MySQL community you can always contribute to improve the process by reading the documentation and logging any issues as Documentation Bugs.

Some time ago in a discussion with a friend and colleague, we were talking about changes in historical defaults that had been improved finally in MySQL 5.4 The specific discussion was on the …

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Cloud openness contemplated
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I caught some of the keynotes and discussion at the Linux Foundation Collaboration Summit today, and was particularly interested in the panel discussion on open source and cloud computing. While we are used to hearing and talking about how important open source software is to cloud computing (open source giving to cloud computing), moderator John Mark Walker posed the question of whether cloud computing gives back? The discussion also rightfully focused on openness in cloud computing, how open source might or might not translate to cloud openness and the importance of data to be …

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10 Newer Entries Showing entries 61 to 70 of 110 10 Older Entries

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