… new tools using their environments. One tool that I am finding very helpful is called SchemaSpy. SchemaSpy is … for dropping (why keep old data if you don’t need to?). I get up to speed a … it is explicit. This has an impact on how SchemaSpy identifies the relationship, and whether you need …
Post: Percona Live MySQL Conference and Expo 2013: It feels like 2007 again
March 21, 2013 By Leave a Comment
… this year’s conference I am going to give a tutorial titled, “Percona XtraBackup: Old and New Features.” I actually traded my other talk… the Community Networking Reception). I am personally looking forward to another lengthy discussion with Dimitri Kravtchuk on how benchmarks should be run, what…
Post: How (not) to find unused indexes
October 16, 2009 By 2 Comments
… can not filter out enough rows to be effective. I see this a lot in consulting issues where customers have… case, MySQL flipped from tablescan to index at about 34%. How am I supposed to find unused indexes then? You really have to… were mentioned from all indexes known. There’s an old tool called mysqlidxchx which should be able to do this.
Post: AUTO_INCREMENT and MERGE TABLES
September 11, 2008 By Leave a Comment
… the value 3 to the new row. Let us see how stable merge table auto_increment values are by truncating the… | Create Table | +——-+————————————————————————————————————————————————————————+ | am | CREATE TABLE `am` ( `i` int(10) unsigned NOT NULL auto_increment, PRIMARY KEY (`i`) ) ENGINE=MRG… TABLE may continue having old file descriptors open not seeing changes done to original table: mysql> select * from am; +—–+ | i | +—–+ | 2 | | 3 | | 5…
Post: How to debug long-running transactions in MySQL
March 8, 2011 By 6 Comments
…. #!/bin/bash # Begin by deleting things more than 7 days old find /root/tcpdumps/ -type f -mtime +7 -exec rm -f… ${host} is blocking” port=$(echo ${host} | cut -d: -f2) tcpdump -i eth0 -s 65535 -x -nn -q -tttt port 3306 and… its inception. That case is still open and I am still stumped as to how a SELECT-only transaction can possibly have undo…
Comment: How MySQL Query Cache works with Transactions
December 20, 2011 By 5 Comments
I am looking to tune a highly transactional messaging database and on most of my servers I turn on query cache and tune it…so that I know how to do. My question is I can’t have people viewing old data, I need them to view…
Post: MySQL 5.6 vs MySQL 5.5 and the Star Schema Benchmark
March 11, 2013 By 7 Comments
… highlight how a data set much larger than the buffer pool may perform worse with innodb_old_blocks_time=1000, but as I… this from happening, another variable innodb_old_blocks_time was introduced. Innodb_old_blocks_time controls how long a page must be on…_old_blocks_time change the performance? Each “flight” of queries represents a set of drill-down queries to find an anomaly. I am…
Post: High availability for MySQL on Amazon EC2 – Part 4 - The instance restart script
August 19, 2010 By 6 Comments
… MySQL. This blog post describes the instance restart script. Remember, I am more a DBA than a script writer so it might… actually “terminated”. The code below is how the script performs this task. #wait until the old instance is terminated it takes a… | egrep “running|pending” | tail -n 1 | cut -d’|’ -f3` if [ "$OLD_INSTANCE_ID" == "" ] then #no running instance : else ec2-terminate-instances…
Post: Troubleshooting MySQL Upgrade Performance Regressions
February 15, 2012 By Leave a Comment
… understand what has changed and what exactly changed for worse. I am speaking about MySQL upgrade – version change but in a lot… likely able to repeat the problem by running query on old and new MySQL Server version and observing the difference. Sometimes… pick the old plan no matter how you try and you might be forced to change your application by changing how query is…
Post: DROP TABLE and stalls: Lazy Drop Table in Percona Server and the new fixes in MySQL
June 22, 2012 By 33 Comments
… this blog post I am going to give a high level picture of how Lazy Drop Table works and how the new DROP Table… Table in MySQL >= 5.5.23 work, I would like to mention quickly, that how drop table in MySQL < 5.5.23... are not as regular and as low as in the old implementation of drop table, but the “Lazy Drop Table” implementation…
