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Displaying posts with tag: usability (reset)

MySQL defaults evolution
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MySQL, the original brand, the one developed by the MySQL team at Oracle, is steadily evolving. You can feel it if you try every new release that comes out of the milestone release cycle. Or even if you don’t try all of them, just testing a release once in a while gives you something to think about.

The engineers at Oracle are trying hard to improve the defaults. If you are the out-of-the-box type, and just install the new version on top of the previous one, leaving the same setup in place, you may be up for a for a few surprises. It’s the marketing, see? They tell you that just by replacing your old MySQL (5.1 or 5.5) with MySQL 5.6 you get 30% to 70% performance improvement. Which happens to be true, not only because the server is better, but also because they have changed the defaults. However, this change in

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Old and new MySQL verbosity
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I was pleased to see Morgan’s announcement about a fix to an old problem of mine. In March 2012 I complained about MySQL verbosity during installation.

In MySQL 5.7.3, this behavior was changed. While the default is still as loud as it can, you can now add an option (log_error_verbosity) to send only errors to STDERR, which allows you to hide the output of mysql_install_db, and still get the errors, if they occur.

Well done!

However, the same obnoxious verbosity is also in MariaDB 10.0.x. Since I discussed this specific bug with a few MariaDB developers early in 2012, I was disappointed to see this same output when running mysql_install_db with MariaDB.

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Parallel replication: off by one
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One of the most common errors in development is where a loop or a retrieval by index falls short or long by one unit, usually because of an oversight or a logic in coding.

Of the following snippets, which one will run 10 times?

/* #1 */    for (N = 0 ; N < 10; N++) printf("%d\n", N);

/* #2 */ for (N = 0 ; N <= 10; N++) printf("%d\n", N);

/* #3 */ for (N = 1 ; N <= 10; N++) printf("%d\n", N);

/* #4 */ for (N = 1 ; N < 10; N++) printf("%d\n", N);

The question is deceptive, as there are two snippets that will run 10 times (1 and 3). But they will print different numbers. If you ware aiming for numbers from 1 to 10, only #3 is good.

After many years of programming, off-by-one errors are rare in my code, and I have been able to spot








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Welcome Tungsten Replicator 2.1.0!
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Overview


First off, the important news. Tungsten Replicator 2.1.0 was released today.
You can download it and give it a try right now.


Second, I would say that I am quite surprised at how much we have done in this release. The previous release (2.0.7) was in February, which is just a few months ago, and yet it looks like ages when I see the list of improvements, new features and bug fixes in the Release Notes. I did not realized it until I ran my last batch of checks to test the upgrade from the previous release, which I hadn’t run for quite a long





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Installing and administering Tungsten Replicator - Part 2 : advanced
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Switching roles

To get a taste of the power of Tungsten Replicator, we will show how to switch roles. This is a controlled operation (as opposed to fail-over), where we can decide when to switch and which nodes are involved.

In our topology, host1 is the master, and we have three slaves. We can either ask for a switch and let the script select the first available slave, or tell the script which slave should be promoted. The script will show us the steps needed to perform the operation.

IMPORTANT! Please note that this operation is not risk free. Tungsten replicator is a simple replication system, not a complete management tool like Continuent Tungsten. WIth the replicator, you must make sure that the applications have stopped writing to the master before starting the switch, and then you

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Parallel replication and GTID - A tale of two implementations
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MySQL 5.6 is probably the version of MySQL with the biggest bundle of new features. You may want to try it soon, since it's now released as GA, and I would like to offer some practical experience on how to use some of the advanced features.

Since replication is my main interest, I will focus on some of the new features in this field, and I will compare what's available in MySQL 5.6 with Tungsten Replicator.

The focus of the comparison is usability, manageability, and some hidden functionality. Parallel replication has been available with Tungsten Replicator for almost two years, and Global Transaction Identifiers for much longer than that. With MySQL 5.6, it seems that the MySQL team wants to close the gap. While the main feature (parallel execution threads) is available and performing well, there are some

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MySQL Sandbox 3.0.30 - now adapted to work with 5.5.30 and 5.6.10
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The latest releases of MySQL Sandbox, in addition to deal with minor bugs, have mostly been necessary because of compatibility issues in MySQL, both 5.5 and 5.6.

When I found that MySQL 5.6 has some InnoDB tables inside the 'mysql' schema, I had to change the way that the sandbox used to remove all contents (the ./clear command.)

To achieve a smooth clean up, MySQL Sandbox now performs a dump of the mysql schema, and uses that saved data to restore the schema after a complete wipeout.

Unfortunately, when 5.5.30 was released, this operation resulted in a warning, due to a behavioral change.

After a careful change, and about 1200 unit tests, the latest version of MySQL Sandbox should work well with every MySQL release from 5.0 to 5.6.

MySQL and warnings - Yet another compatibility break
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The MySQL team seems to have a very peculiar idea about defaults and compatibility. Recently, I wrote about an annoying warning that cannot be removed. And previously, I noticed that MySQL 5.6 mixes warnings, info lines and errors in the same bunch of excessive chattiness.

With MySQL 5.5.30 came another headache. When I run a mysqldump of the 'mysql' schema, I get this warning:

$. mysqldump mysql > m.sql
-- Warning: Skipping the data of table mysql.event. Specify the --events option explicitly.

OK. No big deal. What if I tell the little troublemaker that I DON'T WANT the events table?

$ mysqldump --skip-events mysql > m.sql
--


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Google Docs sharing and its cloudy usability
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Background: SkySQL is a distributed company. Nearly all of us work from home. To be productive, we need to emulate the best aspects of collaborating as if we were working next to one another. Given that nearly all of us had worked under similar distributed conditions at MySQL AB, we knew what we were getting into when we were founded. Obviously, we wanted to learn from our past experiences when making our choices for tools and processes.

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MySQL 5.6 too verbose when creating data directory
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When I install a MySQL package using MySQL Sandbox, if everything goes smoothly, I get an informative message on standard output, and I keep working.

This is OK


$HOME/opt/mysql/5.5.15/scripts/mysql_install_db --no-defaults \
--user=$USER --basedir=$HOME/opt/mysql/5.5.15 \
--datadir=$HOME/sandboxes/msb_5_5_15/data \
--lower_case_table_names=2
Installing MySQL system tables...
OK
Filling help tables...
OK

To start mysqld at boot time you have to copy
support-files/mysql.server to the right place for your system

PLEASE REMEMBER TO SET A PASSWORD FOR THE MySQL root USER !
To do so, start the server, then issue the following commands:

/Users/gmax/opt/mysql/5.5.15/bin/mysqladmin -u root password 'new-password'















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Showing entries 1 to 10 of 28 10 Older Entries

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