Percona Services

Seconds_Behind_Master fluctuating wildly? Check for events caught in a loop

Recently I was working with a customer where we noticed that Seconds_Behind_Master fluctuating from an expected value of 0 seconds behind to a fairly high six figure value.  The servers were configured in a master-master relationship and used 5 figure server_id values, and we had just migrated this cluster from one data centre to […]

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One more InnoDB gap lock to avoid

While troubleshooting deadlocks for a customer, I came around an interesting situation involving InnoDB gap locks. For a non-INSERT write operation where the WHERE clause does not match any row, I expected there should’ve been no locks to be held by the transaction, but I was wrong. Let’s take a look at this table […]

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MySQL Error: Too many connections

MySQL Error: Too many connections

Editor’s Note: Follow up to this post here MySQL 5.7 Performance Tuning After Installation.
We have always received quite a few questions here at wait_timeout is an important parameter to tune and discard unused or idle connections to minimize the number of active connections to your MySQL server – and this will ultimately help to […]

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Percona XtraBackup – A workaround to the failed assertion bug

I recently conducted a test backup of my “master-slave” setup in my VirtualBox as I was migrating from Percona XtraBackup v2.2.0 rev. 4885. However, doing the backup on my slave, I encountered this problem:

Shell

[04] Compressing and streaming ./test/checksum.ibd
[01] Compressing and streaming ./mysql/slave_master_info.ibd
Assertion “to_read % cursor->page_size == 0” failed at fil_cur.cc:293
innobackupex: Error: The xtrabackup child […]

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Innotop: A real-time, advanced investigation tool for MySQL

GUI monitoring tools for MySQL are not always suitable for all our needs or situations. Most of them are designed to provide historical views into what happens to our database over time rather then real-time insight into current MySQL server status. Excellent free tools for this include Nagios, etc. But each of them needs […]

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