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Displaying posts with tag: innodb (reset)

Some current MySQL Architecture writings
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So, I’ve been looking around for a while (and a few times now) for any good resources that cover a bunch of MySQL architecture and technical details aimed towards the technically proficient but not MySQL literate audience. I haven’t really found anything. I mean, there’s the (huge and very detailed) MySQL manual, there’s the MySQL Internals manual (which is sometimes only 10 years out of date) and there’s various blog entries around the place. So I thought I’d write something explaining roughly how it all fits together and what it does to your system (processes, threads, IO etc).(Basically, I’ve found myself explaining this enough times in the past few years that I should really write it down and just point people to my blog).

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OpenStack users shed light on Percona XtraDB Cluster deadlock issues
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I was fortunate to attend an Ops discussion about databases at the OpenStack Summit Atlanta this past May as one of the panelists. The discussion was about deadlock issues OpenStack operators see with Percona XtraDB Cluster (of course this is applicable to any Galera-based solution). I asked to describe what they are seeing, and as it turned out, nova and neutron uses the SELECT … FOR UPDATE SQL construct quite heavily. This is a topic I thought was worth writing

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When (and how) to move an InnoDB table outside the shared tablespace
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In my last post, “A closer look at the MySQL ibdata1 disk space issue and big tables,” I looked at the growing ibdata1 problem under the perspective of having big tables residing inside the so-called shared tablespace. In the particular case that motivated that post, we had a customer running out of disk space in his server who was looking for a way to make the ibdata1 file shrink. As you may know, that file (or, as explained there, the set of ibdata files composing the shared tablespace) stores all InnoDB tables created when innodb_file_per_table is disabled, but also other InnoDB structures, such as undo logs and data dictionary.

For example, when you run a transaction involving

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When (and how) to move an InnoDB table outside the shared tablespace
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In my last post, “A closer look at the MySQL ibdata1 disk space issue and big tables,” I looked at the growing ibdata1 problem under the perspective of having big tables residing inside the so-called shared tablespace. In the particular case that motivated that post, we had a customer running out of disk space in his server who was looking for a way to make the ibdata1 file shrink. As you may know, that file (or, as explained there, the set of ibdata files composing the shared tablespace) stores all InnoDB tables created when innodb_file_per_table is disabled, but also other InnoDB structures, such as undo logs and data dictionary.

For example, when you run a transaction involving InnoDB tables,

  [Read more...]
A closer look at the MySQL ibdata1 disk space issue and big tables
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A recurring and very common customer issue seen here at the Percona Support team involves how to make the ibdata1 file “shrink” within MySQL. I can only imagine there’s a degree of regret by some of the InnoDB architects on their design decisions regarding disk-space management by the shared tablespace* because this has been a big frustration for many MySQL users over the years.

There’s a very old bug (“InnoDB ibdata1 never shrinks after data is removed,” Sept. 8 2003) documenting user dissatisfaction. Shortly before that issue celebrated its 10th anniversary, James Day, MySQL senior principal support engineer at Oracle, posted a comment

  [Read more...]
A closer look at the MySQL ibdata1 disk space issue and big tables
+0 Vote Up -0Vote Down

A recurring and very common customer issue seen here at the Percona Support team involves how to make the ibdata1 file “shrink” within MySQL. I can only imagine there’s a degree of regret by some of the InnoDB architects on their design decisions regarding disk-space management by the shared tablespace* because this has been a big frustration for many MySQL users over the years.

There’s a very old bug (“InnoDB ibdata1 never shrinks after data is removed,” Sept. 8 2003) documenting user dissatisfaction. Shortly before that issue celebrated its 10th anniversary, James Day, MySQL senior principal support engineer at Oracle, posted a comment explaining

  [Read more...]
Take image from corrupted hard drive
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There are at least two cases when it makes sense to take an image from a corrupted hard drive as soon as possible: disk hardware errors and corrupted filesystem. Faulty hard drives can give just one chance to read a block, so there is no time for experiments. The similar picture with corrupted filesystems. Obviously something went wrong, it’s hard to predict how the operating system will behave next second and whether it will cause even more damage.

Save disk image to local storage

Probably the best and fastest way is to plug the faulty disk into a healthy server and save the disk image locally:

# dd if=/dev/sdb of=/path/on/sda/faulty_disk.img  conv=noerror

Where /dev/sdb is the faulty disk and faulty_disk.img is the image on the healthy /dev/sda disk.

conv=noerrror tells

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Which Compression Tool Should I Use for my Database Backups? (Part I: Compression)
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This week we are talking about size, which is a subject that should matter to any system administrator in charge of the backup system of any project, and in particular database backups.

I sometimes get questions about what should be the best compression tool to apply during a particular backup system: gzip? bzip2? any other?

The testing environment

In order to test several formats and tools, I created a .csv file (comma-separated values) that was 3,700,635,579 bytes in size by transforming a recent dump of all the OpenStreetMap nodes of the European portion of Spain. It had a total of 46,741,126 rows and looked like this:

171773  38.6048402      -0.0489871      4       2012-08-25 00:37:46     12850816        472193  rubensd
171774
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Performance evaluation of MariaDB 10.1 and MySQL 5.7.4-labs-tplc
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Introduction

Evaluating the performance of database systems is a very demanding task. There are a lot of hard choices to be made, e.g.:

  • What operating system and operating system version is to be used
  • What configuration setup is to be used
  • What benchmarks are to be used and how long are the warm-up and measure times
  • What test setups are to be used
  • What version of the database management system is used
  • What storage engine is used

While performance evaluation is mostly machine time, there is still a lot of hard work for the human monitoring the tests. In this blog post we have made following choices:

  • We’re using an Intel Xeon E5-2690 @ 2.9GHz CPU containing 32-cores and Linux 3.4.12 with 132G main memory. The database is stored on a Fusion-IO ioDrive2 Duo 2.41TB
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Recover Corrupt MySQL Database
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The unDROP for InnoDB tool can used to recover corrupt MySQL database. In this post we will show how to repair MySQL database if its files became corrupted and even innodb_force_recovery=6 doesn’t help.

The corruption of InnoDB tablespace may be caused by many reasons. A dying hard drive can write garbage, thus page checksum will be wrong. InnoDB then reports to the error log:

InnoDB: Database page corruption on disk or a failed
InnoDB: file read of page 4.

MySQL is well know for poor start-up script. A simple upgrade procedure may end up with two mysqld processes writing to the same tablespace. That leads to the corruption too. Sometimes power reset

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Showing entries 1 to 10 of 759 10 Older Entries

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