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When EXPLAIN estimates can go wrong!

 | October 13, 2011 |  Posted In: MySQL

I have been working with a few customer cases and one interesting case popped up. The customer was facing a peculiar problem where the rows column in the EXPLAIN output of the query was totally off. The actual number of rows was 18 times more than the number of rows reported by MySQL in the […]

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Infinite Replication Loop

 | October 10, 2011 |  Posted In: MySQL

Last week I helped 2 different customers with infinite replication loops. I decided to write a blog post about these infinite loop of binary log statements in MySQL Replication. To explain what they are, how to identify them… and how to fix them.

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Understanding Indexing – NY Effective MySQL Meetup

 | October 7, 2011 |  Posted In: Tokutek, TokuView

At next week’s NY Effective MySQL Meetup, I will give a talk: “Understanding Indexing: Three rules on making indexes around queries to provide good performance.” The meetup is 7 pm Tuesday, October 11th, and will be held at Hive at 55 (55 Broad Street, New York, NY). Thanks to host Ronald Bradford for the invitation. […]

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When Does InnoDB Update Table Statistics? (And When It Can Bite)

 | October 6, 2011 |  Posted In: Insight for DBAs, Insight for Developers, MySQL

An InnoDB table statistics is used for JOIN optimizations and helping the MySQL optimizer choose the appropriate index for a query. If a table’s statistics or index cardinality becomes outdated, you might see queries which previously performed well suddenly show up on slow query log until InnoDB again updates the statistics. But when does InnoDB […]

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Write Optimization: Myths, Comparison, Clarifications, Part 2

 | October 4, 2011 |  Posted In: Tokutek, TokuView

In my last post, we talked about the read/write tradeoff of indexing data structures, and some ways that people augment B-trees in order to get better write performance. We also talked about the significant drawbacks of each method, and I promised to show some more fundamental approaches. We had two “workload-based” techniques: inserting in sequential […]

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Percona Server 5.5.15 + Galera 21.1-beta2

 | October 3, 2011 |  Posted In: Insight for DBAs, MySQL, Percona Software

Codership team published beta2 of MySQL 5.5.15 with Galera replication https://launchpad.net/codership-mysql and we made port to Percona Server: source code: lp:~percona-dev/percona-server/percona-server-galera-5.5.15 binaries for RedHat/CentOS 6: https://www.percona.com/downloads/TESTING/Galera/Percona-XtraDB-Galera-5.5.15.tar.gz What difference between Percona Server+Galera and MySQL 5.5.15 ? First of course, Percona Server+Galera is based on our XtraDB engine. Second, we provide wsrep_sst_xtrabackup script, which allows to use […]

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