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Search Results for: left joins mysql

Interactive Debugging of Transaction Conflicts with TokuDB

I am developing a concurrent application that uses TokuDB to store its database. Sometimes, one of my SQL statements returns with a ‘lock wait timeout exceeded’ error. How do I identify the cause of this …

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Percona XtraDB Cluster (PXC) in the real world: Share your use cases!

The aim of this post is to enumerate real-world usage of Percona XtraDB Cluster (PXC), and also to solicit use cases from the readers. One of the prominent usages in the production environment that we …

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April is the Coolest Month

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If T.S. Eliot were a MySQL DBA, I think he would have been more upbeat about April. We are gearing up for an incredible second half of April. We will be presenting three separate sessions …

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XLDB Tutorial on Data Structures and Algorithms

Next week Michael and I (Bradley) will be travelling to Silicon Valley to present a tutorial on Data Structures and Algorithms for Big Databases at the 6th XLDB Conference. The tutorial, which is 4 hours …

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Top Ten for 2011

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  It’s almost the end of the year – that means holiday cards, shopping, cooking, parties, and the inevitable year-end top lists (including gems like this one). In the spirit of end of year list …

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Is there a performance difference between JOIN and WHERE?

I’ve heard this question a lot, but never thought to blog about the answer. “Is there a performance difference between putting the JOIN conditions in the ON clause or the WHERE clause in MySQL?” No, …

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Improving TPC-H-like Queries – Q2

Posted by Bradley C. Kuszmaul and David Wells Executive Summary: A MySQL straight join can speed up a query that is very similar to TPC-H Q2 by a factor of 159 on MySQL. Recently, we …

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To pack or not to pack – MyISAM Key compression

MyISAM storage engine has key compression which makes its indexes much smaller, allowing better fit in caches and so improving performance dramatically. Actually packed indexes not a bit longer rows is frequent reason of MyISAM …

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