…events ? If you can’t get fancy graph quickly you can…allows you to limit size of MEMORY tables (the limit applies … 2623331) File system 294352 (82672 + 211680) Lock system 318875832 (318747272 + 128560) Recovery system … your MySQL Support contract can be handy. Conclusion Understanding where MySQL …
Post: Percona Toolkit 2.1 with New Online Schema Change Tool
April 5, 2012 By 9 Comments
…MySQL locks tables for most ALTER operations, but pt-online-schema-change performs the ALTER without any locking…. even without advertisement. However, it had many limitations and missing features. The new 2.1… documentation, discuss it on the mailing list, get the source code from Launchpad, and file…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
… is installed, and use it to get information about the physical drives installed; …mysql –user=mysql –pid-file=/var/run/mysqld/mysqld.pid –skip-external-locking –port=3306 –socket=/var/db/mysql/mysql…slow query log output. The stock MySQL server’s limitation of one-second granularity makes …
Post: Modeling MySQL Capacity by Measuring Resource Consumptions
March 8, 2011 By 1 Comment
… resources system has will place a limit on amount of queries system can…get CPU consumption per query ? You can take a look at procfs for MySQL process: root@ubuntu:/var/log/mysql… ======= ======= ======= ======= ======= # Exec time 8338s 1us 284s 5ms 13ms 298ms 185us # Lock time 71s 0 3ms 39us 54us …
Post: How to debug long-running transactions in MySQL
March 8, 2011 By 6 Comments
…then other transactions could block and fail with a lock wait timeout. The problem is, it can be …MB_THRESHOLD=100 # Make sure the disk isn’t getting too full. avail=$(df -m -P /root/tcpdumps/ | …_schema.processlist p on b.trx_mysql_thread_id = p.ID LIMIT 1′) if [ "${host}" ]; then echo “Host ${host…
Post: MySQL Limitations Part 4: One thread per connection
October 27, 2010 By 14 Comments
… limiting MySQL in core use cases (links: part 1, 2, 3). This post is about the way MySQL… it. And with 5000 connections open, you get 5000 threads in the server. That increases …MySQL 6.0, but is available now in MariaDB. Unfortunately it isn’t a full solution, because it can cause undesirable lock…
Post: How much memory can MySQL use in the worst case?
February 12, 2009 By 17 Comments
… keys for user locks! I set my max_allowed_packet bigger and ran the following on my laptop: mysql> set @a := repeat(‘a’, 1024 * 1024 * 100); Query OK, 0 rows affected (2.34 sec) mysql> select get_lock(@a, 1); +—————–+ | get_lock(@a… be because there are some things that have no defined limits. It’s not something that’s worth worrying about much…
Post: Watch out for your CRON jobs
October 14, 2009 By 19 Comments
… locks (do not just create files, files left after script crash can prevent it from starting again) or using GET_LOCK function in MySQL… Availability Purposes). It is also helpful if you want to limit concurrency for certain processes – like if you have 50 web… happens because the amount of “work” increases or because system gets slower in processing this work. It is good if you…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
… ======= ======= ======= ======= ======= # Exec time 8s 1us 44ms 403us 541us 2ms 98us # Lock time 968ms 0 11ms 48us 119us…MySQL. The end result might be that you end up limiting the number of results returned by the query, by using a LIMIT…, I can make out is “Get yourself Percona Server, turn on…
Post: MySQL Users Conference - Innodb
May 9, 2007 By 6 Comments
… version. Relaxing Locks Row level replication allows to get relaxed locks in many other cases. Gap or next-key locks which limit concurrency in many cases can be removed for READ-COMMITED isolation mode which will start offering more performance benefits in MySQL… a lot of “Gotches” while many of them come from MySQL limits at the time when Innodb was first implemented. Many other…
