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Search Results for: join using temporary

A case for MariaDB’s Hash Joins

MariaDB 5.3/5.5 has introduced a new join type “Hash Joins” which is an implementation of a Classic Block-based Hash Join Algorithm. In this post we will see what the Hash Join is, how it works …

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Using Flexviews – part one, introduction to materialized views

If you know me, then you probably have heard of Flexviews. If not, then it might not be familiar to you. I’m giving a talk on it at the MySQL 2011 CE, and I figured …

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Enum Fields VS Varchar VS Int + Joined table: What is Faster?

Really often in customers’ application we can see a huge tables with varchar/char fields, with small sets of possible values. These are “state”, “gender”, “status”, “weapon_type”, etc, etc. Frequently we suggest to change such fields …

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Be careful when joining on CONCAT

The other day I had a case with an awful performance of a rather simple join. It was a join on tb1.vid = CONCAT(‘prefix-‘, tb2.id) with tb1.vid – indexed varchar(100) and tb2.id – int(11) column. …

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Advanced Query Tuning in MySQL 5.6 and MySQL 5.7 Webinar: Q&A

Thank you for attending my July 22 webinar titled “Advanced Query Tuning in MySQL 5.6 and 5.7” (my slides and a replay available here). As promised here is the list of questions and my answers …

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MySQL is crashing: a support engineer’s point of view

In MySQL QA Episode #12, “MySQL is Crashing, now what?,” Roel demonstrated how to collect crash-related information that will help Percona discover what the issue is that you are experiencing, and fix it. As a Support …

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The Q&A: Creating best-in-class backup solutions for your MySQL environment

Thank you for attending my July 15 webinar, “Creating Best in Class Backup solutions for your MySQL environment.” Due to the amount of content we discussed and some minor technical difficulties faced near the end …

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Speed up GROUP BY queries with subselects in MySQL

We usually try to avoid subselects because sometimes they force the use of a temporary table and limits the use of indexes. But, when is good to use a subselect? This example was tested over …

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Diagnosing SST errors with Percona XtraDB Cluster for MySQL

State Snapshot Transfer (SST) is used in Percona XtraDB Cluster (PXC) when a new node joins the cluster or to resync a failed node if Incremental State Transfer (IST) is no longer available. SST is …

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Percona XtraDB Cluster 5.6.21-25.8 is now available

Percona is glad to announce the new release of Percona XtraDB Cluster 5.6 on Novmeber 25th 2014. Binaries are available from downloads area or from our software repositories. We’re also happy to announce that Ubuntu …

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