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Displaying posts with tag: innodb (reset)
Fun with Bugs #47 - On Some Bugs Found Using oprofile

Users had to identify the reasons for MySQL performance problems somehow well before famous Performance Schema appeared in MySQL 5.5.3, and even before Domas invented his Poor Man's Profiler. Poor users had to use some OS-level tools, and among these tools the most important one was, probably, oprofile.

oprofile is a system-wide statistical profiling tool for Linux available since 2001 and 2.4.x kernels. It was applied to MySQL for many …

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The Impact of Swapping on MySQL Performance

In this blog, I’ll look at the impact of swapping on MySQL performance. 

It’s common sense that when you’re running MySQL (or really any other DBMS) you don’t want to see any I/O in your swap space. Scaling the cache size (using

innodb_buffer_pool_size

 in MySQL’s case) is standard practice to make sure there is enough free memory so swapping isn’t needed.   

But what if you make some mistake or miscalculation, and swapping happens? How much does it really impact performance? This is exactly what I set out to investigate.

My test system has the following:

  • 32GB of physical memory
  • OS (and swap space) on a (pretty old) Intel 520 SSD device
  • Database stored on Intel 750 NVMe storage

To simulate a worst case scenario, I’m using Uniform Sysbench Workload:

sysbench …
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Millions of Queries per Second: PostgreSQL and MySQL’s Peaceful Battle at Today’s Demanding Workloads

This blog compares how PostgreSQL and MySQL handle millions of queries per second.

Anastasia: Can open source databases cope with millions of queries per second? Many open source advocates would answer “yes.” However, assertions aren’t enough for well-grounded proof. That’s why in this blog post, we share the benchmark testing results from Alexander Korotkov (CEO of Development, Postgres Professional) and Sveta Smirnova (Principal Technical Services Engineer, Percona). The comparative research of PostgreSQL 9.6 and MySQL 5.7 performance will be especially valuable for environments with multiple databases.

The idea behind this research is to provide an honest comparison for the two popular RDBMSs. Sveta and Alexander wanted to test the most recent versions of both MySQL and PostgreSQL with the same tool, under the same challenging …

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Fun with Bugs #46 - On Some Bugs I've Reported During the Year of 2016

It's time to summarize the year of 2016. As a kind of a weird summary, in this post I'd like to share a list of MySQL bug reports I've created in 2016 that are still remaining "Verified" today:

  • Bug #79831 - "Unexpected error message on crash-safe slave with max_relay_log_size set". According to Umesh this is not repeatable with 5.7. The fact that I've reported the bug on January 4 probably means I was working at that time. I should not repeat this mistake again next year.
  • Bug #80067 - "Index on BIT column is NOT used when column name only is used in WHERE clause". People say the same problem happens with INT and, what may be even less expected, BOOLEAN columns.
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Using Percona XtraBackup on a MySQL Instance with a Large Number of Tables

In this blog post, we’ll find out how to use Percona XtraBackup on a MySQL instance with a large number of tables.

As of Percona Xtrabackup 2.4.5, you are required to have enough open files to open every single InnoDB tablespace in the instance you’re trying to back up. So if you’re running innodb_file_per_table=1, and have a large number of tables, you’re very likely to see Percona XtraBackup fail with the following error message:

InnoDB: Operating system error number 24 in a file operation.
InnoDB: Error number 24 means 'Too many open files'
InnoDB: Some operating system error numbers are described at http://dev.mysql.com/doc/refman/5.7/en/operating-system-error-codes.html
InnoDB: File ./sbtest/sbtest132841.ibd: 'open' returned OS error 124. Cannot continue operation
InnoDB: Cannot …
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Testing (again) LOAD DATA on MySQL 5.6, 5.7, 8.0 (non-GA) and MariaDB 10.0, 10.1 and 10.2 (non-GA)

I’ve been lately compiling and generating .deb packages for several MySQL and MariaDB recent versions, and I wanted to try them more in depth -specially MySQL 8.0 and MariaDB 10.2, both of which are still in development.

Several people have already given their first impressions (or will do soon), and testing early is the best way to catch bugs and regressions, and get them fixed before the official release. In fact, as I will comment later, I ran into breaking bugs on both MySQL 8.0 and MariaDB 10.2, which I …

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Make MySQL 8.0 Better Through Better Benchmarking

This blog post discusses how better MySQL 8.0 benchmarks can improve MySQL in general.

Like many in MySQL community, I’m very excited about what MySQL 8.0 offers. There are a lot of great features and architecture improvements. Also like many in the MySQL community, I would like to see MySQL 8.0 perform better. Better performance is what we always want (and expect) from new database software releases.

Rarely do performance improvements happen by accident – they require running benchmarks, finding bottlenecks and eliminating them. This is the area where I think things could use improvement.

If you come to the MySQL Keynote at Oracle OpenWorld, or if you go to MySQL …

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Using the InnoDB Buffer Pool Pre-Load Feature in MySQL 5.7

In this blog post, I’ll discuss how to use the InnoDB buffer pool pre-load feature in MySQL 5.7

Starting MySQL 5.6, you can configure MySQL to save the contents of your InnoDB buffer pool and load it on startup. Starting in MySQL 5.7, this is the default behavior. Without any special effort, MySQL saves and restores a portion of buffer pool in the default configuration. We made a similar feature available in Percona Server 5.5 – so the concept has been around for quite a while.

Frankly, time has reduced the need for this feature. Five years ago, we would typically store databases on spinning disks. These disks often took quite a long time to warm up with normal database workloads, which could lead to …

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Percona Server 5.5.53-38.4 is now available

Percona announces the release of Percona Server 5.5.53-38.4 on November 18, 2016. Based on MySQL 5.5.53, including all the bug fixes in it, Percona Server 5.5.53-38.4 is now the current stable release in the 5.5 series.

Percona Server is open-source and free. You can find release details in the 5.5.53-38.4 milestone on Launchpad. Downloads are available here and from the Percona Software Repositories.

Removed Features:

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MySQL Support Engineer's Chronicles, Issue #3

The original idea of this series was to publish one post per week, but it seems every other week I have some special topic that well deserves a dedicated post. Last week I had no time to complete my writing because of long (and, I hope, useful) Howto post on replacing corrupted partition using non-corrupted one from other server in replication setup. But I had links and notes collected in a draft that I am going to complete now.

First of all, during the previous week I had time to submit two more talks for the  …

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