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Showing entries 1 to 10 of 407 10 Older Entries

Displaying posts with tag: Insight for DBAs (reset)

MySQL indexing 101: a challenging single-table query
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We discussed in an earlier post how to design indexes for many types of queries using a single table. Here is a real-world example of the challenges you will face when trying to optimize queries: two similar queries, but one is performing a full table scan while the other one is using the index we specially created for these queries. Bug or expected behavior? Read on!

Our two similar queries

# Q1
mysql> explain select col1, col2 from t where ts >= '2015-04-30 00:00:00'; …
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Keep your MySQL data in sync when using Tungsten Replicator
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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 have regular replication going from master (db1) to 4 slaves (db2, db3, …

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Optimizer hints in MySQL 5.7.7 – The missed manual
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In version MySQL 5.7.7 Oracle presented a new promising feature: optimizer hints. However it did not publish any documentation about the hints. The only note which I found in the user manual about the hints is:

  • It is now possible to provide hints to the optimizer by including /*+ ... */ comments following the …
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Test your knowledge: Percona XtraDB Cluster (PXC) quiz
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I often talk with people who are very interested in the features of Percona XtraDB Cluster (PXC) such as synchronous and parallel replication, multi-node writing and high availability. However some get confused when operating a real PXC cluster because they do not fully realize the implications of these features. So here is a fun way to test your PXC knowledge: try to solve these 12 questions related to PXC! (you will find the answers at the end of the post.)

Workload

1. With Galera 3.x, support for MyISAM is experimental. When can we expect to have full MyISAM support?
a. This will never happen as …

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Indexing 101: Optimizing MySQL queries on a single table
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I have recently seen several cases when performance for MySQL queries on a single table was terrible. The reason was simple: the wrong indexes were added and so the execution plan was poor. Here are guidelines to help you optimize various kinds of single-table queries.

Disclaimer: I will be presenting general guidelines and I do not intend to cover all scenarios. I am pretty confident that you can find examples where what I am writing does not work, but I am also confident that it will help you most of the time. Also I will not discuss features you can find in MySQL 5.6+ like Index Condition Pushdown to keep things …

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Considering Sharding with MySQL? Join my April 22 webinar. Questions welcome!
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MySQL sharding is one of the most used and surely the most abused MySQL scaling technology. My April 2 Dzone article, “To Shard, or Not to Shard,” proved there is indeed quite an interest in this topic.

As such, I’m hosting a live webinar tomorrow (April 22) that will shed light on questions about sharding with MySQL. It’s titled: To Shard or Not to Shard That is the Question!

I’ll be answering …

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Staying ahead of MySQL operational problems at Percona Live
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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 …

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pquery binaries with statically included client libs now available!
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After we released pquery to the community, and as we started logging bug reports with pquery testcases, it quickly became clear that pquery binaries with statically compiled-in client libraries would be of great convenience, both for ourselves and for the community.

(If you haven’t heard about pquery yet, read the pquery introduction blog post, come and join the …

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More on (transactional) MySQL metadata locks
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Two years ago Ovais Tariq had explained in detail what kinds of problems existed before MySQL introduced metadata locks in 5.5.3 and how these locks help to prevent them. Still, some implications of metadata locking in MySQL remain unclear for users – DBAs and even software developers that target recent MySQL versions. I’ve decided to include a slide or two into the …

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MySQL QA Episode 1: Bash/GNU Tools & Linux Upskill & Scripting Fun
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MySQL QA Episode #1: Bash/GNU Tools & Linux Upskill & Scripting Fun

This episode consists of 13 parts, and an introduction. See videos below

In HD quality (set your player to 720p!)

Introduction

Part 1: echo, ls, cp, rm, vi, cat, df, du, tee, cd, clear, uname, date, time, cat, mkdir

Part 2: find, wc, sort, shuf, tr, mkdir, man, more

Part 3: Redirection, tee, stdout, stderr, /dev/null, cat

Part 4: Vars, ‘ vs “, $0, $$, $!, screen, chmod, chown, export, set, whoami, sleep, …

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Showing entries 1 to 10 of 407 10 Older Entries

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