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Displaying posts with tag: Insight for DBAs (reset)
Upcoming Webinar September 14, 2017: Supercharge Your Analytics with ClickHouse

Join Percona’s CTO Vadim Tkachenko @VadimTk and Altinity’s Co-Founder, Alexander Zaitsev as they present Supercharge Your Analytics with ClickHouse on Thursday, September 14, 2017, at 10:00 am PDT / 1:00 pm EDT (UTC-7).

Reserve Your Spot

 

ClickHouse is a real-time analytical database system. Even though they’re only celebrating one year as open source software, it has already proved itself ready for serious …

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Updating InnoDB Table Statistics Manually

In this post, we will discuss how to fix cardinality for InnoDB tables manually.

As a support engineer, I often see situations when the cardinality of a table is not correct. When InnoDB calculates the cardinality of an index, it does not scan the full table by default. Instead it looks at random pages, as determined by options innodb_stats_sample_pages, innodb_stats_transient_sample_pages and innodb_stats_persistent_sample_pages, or …

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This Week in Data with Colin Charles #5: db tech showcase and Percona Live Europe

Join Percona Chief Evangelist Colin Charles as he covers happenings, gives pointers and provides musings on the open source database community.

Percona Live Europe 2017 in Dublin

Have you registered for Percona Live Europe Dublin? We have announced some awesome keynotes, and our sponsor list is growing (and we’re always looking for more!).

There will also be a community dinner (Tuesday, September …

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Upcoming Webinar Thursday, September 7: Using PMM to Troubleshoot MySQL Performance Issues

Join Percona’s Product Manager, Michael Coburn as he presents Using Percona Monitoring and Management to Troubleshoot MySQL Performance Issues on Thursday, September 7, 2017, at 10:00 am PDT / 1:00 pm EDT (UTC-7).

Reserve Your Spot

 

Successful applications often become limited by MySQL performance. Michael will show you how to get great MySQL performance using Percona Monitoring and Management (PMM). There will be a demonstration of how to leverage the combination of the …

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Looking at Disk Utilization and Saturation

In this blog post, I will look at disk utilization and saturation.

In my previous blog post, I wrote about CPU utilization and saturation, the practical difference between them and how different CPU utilization and saturation impact response times. Now we will look at another critical component of database performance: the storage subsystem. In this post, I will refer to the storage subsystem as “disk” (as a casual catch-all). 

The most common tool for command line IO performance monitoring is

iostat

, which shows information like this:

root@ts140i:~# iostat -x nvme0n1 5
Linux 4.4.0-89-generic (ts140i)         08/05/2017      _x86_64_        (4 CPU)
avg-cpu:  %user   %nice %system %iowait  %steal   %idle
          0.51    0.00    2.00    9.45    0.00   88.04
Device:         rrqm/s   wrqm/s …
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Multi-Threaded Slave Statistics

In this blog post, I’ll talk about multi-threaded slave statistics printed in MySQL error log file.

MySQL version 5.6 and later allows you to execute replicated events using parallel threads. This feature is called Multi-Threaded Slave (MTS), and to enable it you need to modify the

slave_parallel_workers

 variable to a value greater than 1.

Recently, a few customers asked about the meaning of some new statistics printed in their error log files when they enable MTS. These error messages look similar to the example stated below:

[Note] Multi-threaded slave statistics for channel '': seconds elapsed = 123; events assigned = 57345; worker queues filled over overrun level = 0; waited due a Worker queue full = 0; waited due the total size = 0; waited at clock conflicts = 0 waited (count) …
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A Little Trick Upgrading to MySQL 5.7

In this blog post, I’ll look at a trick we use at Percona when upgrading to MySQL 5.7.

I’ll be covering this subject (and others) in my webinar Learning MySQL 5.7 on Wednesday, July 19, 2017.

We’ve been doing upgrades for quite a while here are Percona, and we try to optimize, standardize and improve this process to save time. When upgrading to MySQL 5.7, more often than not you need to run REPAIR or ALTER via mysql_upgrade to a number of MySQL tables. Sometimes a few hundred, sometimes hundreds of thousands.

One way to cut some time from testing or executing mysql_upgrade is to combine it with mysqlcheck. This identifies tables that need to be rebuilt or repaired. The first …

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Gh-ost benchmark against pt-online-schema-change performance

In this blog post, I will run a gh-ost benchmark against the performance of pt-online-schema-change.

When gh-ost came out, I was very excited. As MySQL ROW replication became commonplace, you could use it to track changes instead of triggers. This practice is cleaner and safer compared to Percona Toolkit’s pt-online-schema-change. Since gh-ost doesn’t need triggers, I assumed it would generate lower overhead and work faster. I frequently called it “pt-online-schema-change on steroids” in my talks. …

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ClickHouse: One Year!

In this blog, we’ll look at ClickHouse on its one year anniversary.

It’s been a year already since the Yandex team released ClickHouse as open source software. I’ve had an interest in this project from the very start, as I didn’t think there was an open source analytical database that could compete with industry leaders like Vertica (for example).

This was an exciting year for ClickHouse early adopters. Let’s look at what it accomplished so far.

ClickHouse initially generated interest due to the Yandex name – the most popular search engine in Russia. It wasn’t long before jaw-dropping responses popped up: guys, this thing is crazy fast! Many early adopters who tried ClickHouse were really impressed.

Fast doesn’t mean convenient …

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Differences in PREPARE Statement Error Handling with Binary and Text Protocol (Percona XtraDB Cluster / Galera)

In this blog, we’ll look at the differences in how a PREPARE statement handles errors in binary and text protocols.

Introduction

Since Percona XtraDB Cluster is a multi-master solution, when an application executes conflicting workloads one of the workloads gets rolled back with a DEADLOCK error. While the same holds true even if you fire the workload through a PREPARE statement, there are differences between using the MySQL connector API (with binary protocol) and the MySQL client (with text protocol). Let’s look at these differences with the help of an example.

Base Workload

  • Say we have a two-node cluster (n1 and n2) with the following base schema and tables:
    use test;
    create table t (i int, k int, primary key pk(i)) engine=innodb;
    insert into t values (1, 10), (2, 20), (3, 30); …
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