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Confusing MySQL Replication Error Message

 | June 4, 2008 |  Posted In: Insight for DBAs

I already wrote about some MySQL Error Messages which are confusing, here is one more:

After setting up new slave Server I’m getting error log file flooded with messages like this and there is no hint in the message what would explain what is wrong. In fact the issue in this case is (because […]

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Tools to use for MySQL Performance Review

 | May 31, 2008 |  Posted In: Insight for DBAs

There are some tools we commonly use doing performance review and optimization and we often ask each other where that particular stuff is located on the web or what is exactly name of the command what does that. Initially I thought creating internal Percona Wiki page, but thought there is no reason this information should […]

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Is DNS the Achilles heel in your MySQL installation?

 | May 31, 2008 |  Posted In: Insight for DBAs

Do you have skip_name_resolve set in your /etc/my.cnf? If not, consider it. DNS works fine, until it doesn’t. Don’t let it catch you off guard. Do you really need to restrict MySQL users based on hostnames? If you don’t, you should probably disable this feature of MySQL’s authentication system. You never know when your hosting […]

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Should you name indexes while doing ALTER TABLE ?

 | May 28, 2008 |  Posted In: Insight for DBAs

MySQL Server does not require you to specify name of the index if you’re running ALTER TABLE statement – it is optional. Though what might be good practical reasons to specify the key name or omit ? Things what you should be looking at is how MySQL names indexes automatically as well as what maintaining […]

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INFORMATION_SCHEMA tables in the InnoDB pluggable storage engine

 | May 24, 2008 |  Posted In: Insight for DBAs

Much has been written about the new InnoDB pluggable storage engine, which Innobase released at the MySQL conference last month. We’ve written posts ourselves about its fast index creation capabilities and the compressed row format, and how that affects performance. One of the nice things they added in this InnoDB release is INFORMATION_SCHEMA tables that […]

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Dangerous command

 | May 20, 2008 |  Posted In: Insight for DBAs

Remembering that I did RENAME DATABASE in MySQL 5.1.21 and found it useful I tried it with 5.1.24 (I was playing with 20GB InnoDB database, so dumping is not fastest way) and all my tries finished with “Syntax error”. So RTMF and documentation says “This statement was added in MySQL 5.1.7 but was found to […]

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Wanted: Better memory profiling for MySQL

 | May 18, 2008 |  Posted In: Insight for DBAs

Quite frequently I would log in to customers system and find MySQL using too much memory. I would look at memory consumed by Innodb (it is often higher than innodb_buffer_pool_size) substract memory used by other global buffers such as query_cache_size and key_buffer and will in many cases see some mysterous memory which I can’t really […]

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Concurrent inserts on MyISAM and the binary log

 | May 14, 2008 |  Posted In: Insight for DBAs

Recently I had an interesting surprise with concurrent inserts into a MyISAM table. The inserts were not happening concurrently with SELECT statements; they were blocking and the process list was filling up with queries in Locked status. My first thought was that the customer had deleted from the table, which leaves “holes” in the middle […]

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