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Displaying posts with tag: MySQL 5.6 (reset)

MySQL 5.6 system variables in the MariaDB 10 server
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Since MariaDB aims to be a compatible/drop-in replacement to MySQL, its crucial that in 10.0 we support all the 5.6 options/system variables, else we have to clearly document them in the Knowledgebase article MariaDB versus MySQL – Compatibility.

To this extent, Sergey Vojtovich (svoj) has created MDEV-5277 as a tracker. There is also plenty of discussion on this topic at the maria-developers mailing list. I encourage current users of MySQL 5.6 to take a look at the list and comment either in Jira or on the mailing list to

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How to recover an orphaned .ibd file with MySQL 5.6
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A few years ago Yves Trudeau and Aleksandr Kuzminsky wrote posts about different ways for recovering orphaned .ibd files:

Today I want to show you how to do that in more easy and quick way. In my example I’ll restore a “payment.ibd” file (payment table) from

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Teaser on my upcoming Percona Live London 2013 session
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As you probably know already, I have a session on PERFORMANCE_SCHEMA at the conference, scheduled at 12 November 4:00pm - 4:50pm @ Orchard 1. Presentation is mostly ready, but I had not decided yet when to publish it. In the meantime, for those really interested, here is a teaser.

Below I list one link for each slide (in order of presentation) having more than one of them mentioned or listed in my notes. Now try to guess what I am going to say there and why. Note that it's not a tutorial (my half a day tutorial on PERFORMANCE_SCHEMA was not accepted by the conference committee, and this is probably good decisions, as I am usually very good in explaining what's bad or what should never be done and much worse in "best practices"). So,

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My Favorite Hidden Docs Page
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There’s a lot to love about the MySQL product documentation – a lot of hard work from a number of very talented Oracle staff goes into it (not to mention the helpful suggestions and feedback from the community).  There is, however, one page I find myself coming back to again and again, despite the fact that it’s somewhat hard to find.  This is the MySQL Server options/variable reference page.  It’s a helpful table that lists every MySQL Server option or variable, what version it was introduced or deprecated in, whether it’s dynamic or not, whether variables have session/global/both scope, and links to the version-specific documentation for that variable (useful to know when default values changed, for example).

It

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InnoDB adaptive flushing in MySQL 5.6: checkpoint age and io capacity
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In MySQL 5.6 InnoDB has a dedicated thread (page_cleaner) that’s responsible for performing flushing operations. Page_cleaner performs flushing of the dirty pages from the buffer pool based on two factors:
- access pattern  -  the least recently used pages will be flushed by LRU flusher from LRU_list when buffer pool has no free pages anymore;
- age – the oldest modified non-flushed pages are part of flush_list structure and will be flushed by flush_list flusher based on several heuristics.

There is a good overview of the page_cleaner and also here you may find some details about



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MySQL 5.6 New Replication Features: Webinar followup Q&A
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I want to thank all attendees of my webinar, “MySQL 5.6 New Replication Features: Benefits, Challenges and Limitations“. We had questions that I didn’t have the time to answer:

Q: If I run on Amazon’s RDS, do I need to worry about enabling crash-safe slaves, or is that already in place?

A: Crash-safe replication is already configured for read replicas using MySQL 5.6.

Q: How the relay log purge will manage in case of

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Using the PAM authentication plugin
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The procedure for using the PAM authentication plugin as documented doesn't work flawlessly on Ubuntu.

So here is how it works on Ubuntu (and probably also on other Debian based systems).

Please note that the PAM authentication plugin is an enterprise feature.

1. Make sure the plugin is loaded

This can be done by adding the following to the mysqld section of my.cnf (Don't forget to restart). You could also use INSTALL PLUGIN to load it without restart.
plugin-load=authentication_pam.so
2.  Add a user which will use the plugin

mysql> CREATE USER 'dveeden'@'localhost' IDENTIFIED WITH authentication_pam;
Query OK, 0 rows affected (0.00 sec)
3. Add a pam config file for 'mysql':
Create












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Recalculating InnoDB Persistent Statistics - a Story of the Bug Report
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One of the first posts in this blog was about reporting MySQL bugs "properly", in a way that maximizes chances for it to be processed really soon. I had written the following there:
"Ideally, you should provide a complete test case and/or instructions that any reader can use to reproduce your problem"
Indeed, if one can just copy/paste something to mysql command line client or run some file attached to see the problem, chances are high for the bug to be processed really soon. We all like to get low hanging fruits from time to time, and Oracle engineers who work on bugs are not exceptions. But does this mean that bug without clear test case has no value and is going to be ignored?

It should NOT be the case. Let's


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time for standards 2
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I was a bit wrong in my previous post. MySQL 5.6 does allow you to supply a fsp with CURRENT_TIMESTAMP (thanks Roy).

mysql> SELECT CURRENT_TIMESTAMP,CURRENT_TIMESTAMP(6);
+---------------------+----------------------------+
| CURRENT_TIMESTAMP | CURRENT_TIMESTAMP(6) |
+---------------------+----------------------------+
| 2013-10-27 10:38:59 | 2013-10-27 10:38:59.182530 |
+---------------------+----------------------------+
1 row in set (0.00 sec)

It however feels a bit weird to me as the CURRENT_TIMESTAMP is often used without () and doesn't look like a function. So when I tried to use a CURRENT_TIMESTAMP with a fsp of 6 it was not behaving how I expected it to be:
mysql> CREATE TABLE t1 (ts TIMESTAMP DEFAULT











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time for standards
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MySQL 5.6 includes support for microsecode timestamp resolution, which is a great new feature.

To get the current timestamp in MySQL 5.5 you could use NOW(), SYSDATE() or CURRENT_TIMESTAMP.

mysql_5.5> SELECT NOW(),SYSDATE(),CURRENT_TIMESTAMP;
+---------------------+---------------------+---------------------+
| NOW() | SYSDATE() | CURRENT_TIMESTAMP |
+---------------------+---------------------+---------------------+
| 2013-10-26 15:46:24 | 2013-10-26 15:46:24 | 2013-10-26 15:46:24 |
+---------------------+---------------------+---------------------+
1 row in set (0.01 sec)

If we run the same statement in MySQL 5.6 the output is the same. This is great for compatibility, but what if we want those microsecond











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10 Newer Entries Showing entries 31 to 40 of 179 10 Older Entries

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