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used_columns: EXPLAIN FORMAT=JSON tells when you should use covered indexes

 | December 14, 2015 |  Posted In: EXPLAIN, EXPLAIN FORMAT=JSON is cool!, JSON, MySQL, MySQL 101

In the “MySQL Query tuning 101” video, Alexander Rubin provides an excellent example of when to use a covered index. On slide 25, he takes the query select name from City where CountryCode = ’USA’ and District = ’Alaska’ and population > 10000 and adds the index cov1(CountryCode, District, population, name) on table City. With Alex’s query tuning experience, making the right index decision is simple – but what about us mere mortals? If a query is more […]

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Why base64-output=DECODE-ROWS does not print row events in MySQL binary logs

 | July 30, 2015 |  Posted In: MySQL, MySQL 101

Lately I saw many cases when users specified option --base64-output=DECODE-ROWS  to print out a statement representation of row events in MySQL binary logs just to get nothing. Reason for this is obvious: option --base64-output=DECODE-ROWS  does not convert row events into its string representation, this is job of option --verbose . But why users mix these […]

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Keep your MySQL data in sync when using Tungsten Replicator

 | May 4, 2015 |  Posted In: Insight for DBAs, MariaDB, MySQL, MySQL 101

MySQL replication isn’t perfect and sometimes our data gets out of sync, either by a failure in replication or human intervention. We are all familiar with Percona Toolkit’s pt-table-checksum and pt-table-sync to help us check and fix data inconsistencies – but imagine the following scenario where we mix regular replication with the Tungsten Replicator: We […]

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Staying ahead of MySQL operational problems at Percona Live

 | April 13, 2015 |  Posted In: Insight for DBAs, MySQL, MySQL 101, Percona Live, Percona Toolkit

I’ve started my long journey from Florianópolis, Brazil, to Santa Clara, California and I type this words while waiting for a connection flight. Next Wednesday, Daniel Guzmán Burgos and I will be presenting in the Percona Live MySQL Conference and Expo (PLMCE). I’m so excited with the new MySQL 101 program that has been added […]

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