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10 Newer Entries Showing entries 31 to 40 of 86 10 Older Entries

Displaying posts with tag: performance_schema (reset)

MySQL Connect and Oracle Open World Presentations Online
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After a slight delay (travel and catching up with “real work”), I’ve now uploaded the talks that I gave at MySQL Connect and Oracle Open World.

They are available on my Presentations Page, and inline below for convenience. The “Introduction to MySQL Enterprise Monitor” talk was actually a full demo, but there are some screenshots of MEM 3.0 in there if you’re interested in seeing a high level picture of what it looks like now.

Thanks to all that attended my talks, I got a lot of good questions and feedback!

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Fun with Bugs #24 - PERFORMANCE_SCHEMA
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It seems that one of my session proposals is accepted for Percona Live London 2013, so I have to prepare myself to speak about PERFORMANCE_SCHEMA new features and problems in MySQL 5.6. Bugs are going to be discussed, among other things. Let's check current active bugs (and some "Not a bug"s) related to PERFORMANCE_SCHEMA in this issue.

I'd like to start with Bug #68514 that got some attention this week again, in despite of its "Not a bug" …

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Understanding max_connect_errors
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To only slightly misquote one of the greatest movies of all times:

You keep using that option.  I do not think it means what you think it means.

 

Perhaps like many users, I had certain assumptions about what max_connect_errors really does – but in looking closely as part of investigating the new PERFORMANCE_SCHEMA.HOST_CACHE table in MySQL 5.6, I learned that some very fundamental elements had escaped my notice.  I’m writing this blog post to help others who hold similar …

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MySQL 5.6 users – prevent host blocked errors
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The much-improved PERFORMANCE_SCHEMA in MySQL 5.6 provides visibility into MySQL’s host cache, including the ability to monitor for impending blocked hosts.  You can do this with the following query:

mysql> SELECT
    ->  ip,
    ->  host,
    ->  host_validated,
    ->  sum_connect_errors
    -> FROM performance_schema.host_cache\G
*************************** 1. row ***************************
                ip: 192.168.2.4
              host: TFARMER-MYSQL.wh.oracle.com
    host_validated: YES
sum_connect_errors: 3
1 row in set …
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Spring Cleaning: Useless protocol commands
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In an earlier post, I commented on clients and utility programs which seem to no longer be useful, and opened (or referenced existing) public bug reports to deprecate and remove, where appropriate.  That effort came actually was the product of a different initiative:  I was looking for clients which might leverage the full spectrum of MySQL protocol commands in an effort to understand whether certain protocol commands are in use.  …

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Practical P_S: Fixing gaps in GLOBAL STATUS
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Over three years ago, I noticed that there was no STATUS counter for COM_PING commands – something that is useful for ensuring proper configuration of JDBC connection pools.  Mark Leith even provided a patch, but it’s never been incorporated.  With the advances PERFORMANCE_SCHEMA makes in MySQL 5.6, that’s OK – a STATUS counter becomes somewhat redundant:

mysql> SELECT SUM(count_star) as pings
    -> FROM events_statements_summary_global_by_event_name …
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Fun with Bugs #21 - recently verified bugs in MySQL 5.6.13
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Notable contribution of MySQL Community to MySQL 5.6.13 was explicitly recognized recently. But users and contributors still continue their efforts, as well as Oracle engineers. Even though MySQL 5.6.13 has been generally available just for few days, we already have several new bug reports and updates to known bugs at http://bugs.mysql.com. Let me present a short list with some comments.



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Practical P_S: How idle are your connections?
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Idle connections can cause problems both at the application side, increasing the risk of connection timeouts for applications where persistent connections are used, and the server side, where resources remain allocated to idle connections.  Any application with persistent connections, such as a JDBC application using a connection pool, will have periods where connections are idle – but it’s good to know how much time is spent idle.  Too much idle time might mean connections pools configured to …

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Practical P_S: How old are your connections?
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I’ve often wished that PROCESSLIST exposed when a connection was first established, and I find myself wishing for this information more now with MySQL 5.6.  Improvements to PERFORMANCE_SCHEMA make it trivial to see how much time is being spent in various operations for a given connection – but it would make some analysis (“what percentage of connection time is spent doing X?”) easier.

That said, it is possible to approximate connection age with PERFORMANCE_SCHEMA in MySQL 5.6.  I say “approximate” because results will vary based on what instrumentation …

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Practical P_S: Finding the KILLer
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In a previous post, I described how to leverage PERFORMANCE_SCHEMA in MySQL 5.6 to identify connections which had not been properly closed by the client.  One possible cause of connections being closed without explicit request from the client is when another process issues a KILL CONNECTION command:

mysql> SHOW GLOBAL STATUS LIKE 'aborted_clients';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| Aborted_clients | 0     |
+-----------------+-------+
1 row in set …
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10 Newer Entries Showing entries 31 to 40 of 86 10 Older Entries

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