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10 Newer Entries Showing entries 61 to 70 of 1153 10 Older Entries

Displaying posts with tag: Databases (reset)

MySQL performance schema threads
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A trap for those new to the MySQL Performance Schema is the expectation that thread_id in tables such as events_statements_current matches the id you find in the MySQL processlist. This is NOT TRUE.

If we look at the INFORMATION_SCHEMA.PROCESSLIST table we will find information like:

mysql> select id,db,command,state from information_schema.processlist order by id;
| id        | db                 | command | state …
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What causes LOST_EVENTS error in the MySQL binary log?
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Using MySQL 5.6.13 under CentOS 6.4, I had a replication failure on one master/slave topology because the master binary log had the following entry that was intentionally written by the MySQL server.

$ mysqlbinlog --start-position=244670849 mysql-bin.000029
# at 244670849
#131028 19:31:38 server id 39  end_log_pos 244670906 CRC32 0xc5d084ec
# Incident: LOST_EVENTS
RELOAD DATABASE; # Shall generate syntax error
# at 244670906

The question is why? I do not know the answer. Searching online indicates this can occur in a MySQL Cluster environment, and can occur around the use of GRANT statements. Neither of these …

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MySQL Workbench “Clean up SQL” Feature
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I was playing around with MySQL Workbench earlier in the week, and ran across the “clean up SQL” feature, which I thought was neat. Here’s a picture-based demonstration – you can click on the pictures to make them bigger, so they are more readable.

Here is a typical complex query that looks pretty good formatted in the results from a performance schema query:

Simply click the “broom” icon and watch as your SQL is cleaned up, with one field in the SELECT per line and the JOINs indented and formatted prettily:

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MySQL/NoSQL/Cloud Conference Latin America
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Last week I was a guest speaker at the second annual MySQL/NoSQL/Cloud Conference held in Buenos Aires, Argentina. Thanks to Santiago Lertora from Binlogic who has taken on the responsibility of organizing a event for the MySQL community in South America.

My presentations slides for my 3 talks.

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Simple Settings for a Saner MySQL – Character Sets
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Character sets are like the force: they surround us and penetrate us, binding all our digital world together. A character set is how we convert the 1’s and 0’s that the computer understands into human-readable characters like ABC. In one of the first character sets, ASCII, the number 97 is translated to “a” and 63 is the question mark (?).

“Are there other languages besides English?”
“Don’t think so, Bob.”

English-Only Please

The trouble with ASCII is that it was created back in the ‘60s by a bunch of Americans and they …

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Simple Settings for a Saner MySQL – Part I
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One day, after taking a job using MySQL, I was writing a query quietly at my desk. It was around quittin’ time, and I was whipping up a new report on the monthly sales figures that the CEO needed for his board meeting in the morning. I, in my ignorance, wrote a nice query with a simple little sum() function. What I did not realize is this caused all my rows to sum up to one row when it really should’ve show several rows. This made my report completely inaccurate. Blindly trusting me as I had blindly trusted MySQL, the CEO presented my report to the board who decided that the company was …

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MySQL Connect presentations on MySQL Fabric available on SlideShare
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Going to MySQL Connect was truly a blast. We got a lot of good questions and feedback in the sessions and there were a lot of interest in both MySQL Fabric and the MySQL Applier for Hadoop.

A big thank you to all that attended the talks, I got a lot of good questions and comments that will help us build good solutions.

The talks are available on SlideShare:

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An unexplained connection experience
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The “Too many connections” problem is a common issue with applications using excessive permissions (and those that grant said global permissions). MySQL will always grant a user with SUPER privileges access to a DB to investigate the problem with a SHOW PROCESSLIST and where you can check the limits. I however found the following.

mysql> show global variables like 'max_connections';
| Variable_name   | Value |
| max_connections | 2000  |
1 row in set (0.00 sec)

mysql> show global status like 'max%';
| Variable_name        | …
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Learn MySQL for Free with MySQL Marinate, Season 3!
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The 3rd season of MySQL Marinate begins October 1st, 2013*. Join the meetup group and RSVP at season 3 to join! You can do the work on MySQL, or if you prefer, MariaDB or Percona.

If you do not have the book yet, you can still do the first week by using the online material from “Browse Contents” on the O’Reilly book page for Learning MySQL. There is homework for week 1, see the …

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A friday MongoDB funny
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I had to laugh (just a bit) at this on the exhibitor floor at Oracle Open World 2013. There was a large MongoDB presence at the Slot 301. There are a few reasons.
First, the identity crisis remains. There is no MongoDB in the list of exhibitors, it’s 10gen, but where is the 10gen representation in the sign. 99.99% of attendees would not know this.
Second, the first and only slide I saw (as shown below), tries to directly compare implementing a solution to Oracle. The speaker made some comment but I really zoned out quickly. Having worked with …

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10 Newer Entries Showing entries 61 to 70 of 1153 10 Older Entries

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