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Displaying posts with tag: innodb (reset)

Online Truncate of InnoDB UNDO Tablespaces
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We have received a lot of requests from our user community regarding the ability to  truncate UNDO tablespaces (‘truncate’ here means that the size of the tablespace is reset back to what it was when it was first created). We are happy to say that we’ve now been able to implement this anticipated feature.

Introduction

The InnoDB UNDO tablespace(s) host rollback segments that hold rollback information related to database changes. This information is used to rollback a transaction and to retrieve the previous version of a record that has been updated or deleted for multi-version concurrency control (MVCC). Once a transaction is committed, InnoDB will discard the related UNDO log records. UNDO log records for updates or deletes will be kept around as long as there exists an open transaction that may access older versions of the records. When all

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About the Data Dictionary Labs Release
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For a long time, the MySQL development community and many others have wanted a server that worked without FRM files.  The motivation behind removing FRM files, and the design goals around new data dictionary, can be explored in more detail in the blog post by Ståle Deraas “A New Data Dictionary for MySQL”.

And now for the good news! We have a MySQL Labs Release ready with a preview of the new Data Dictionary!

What is in the first MySQL Data Dictionary labs release?

First of all, the FRM files are now gone. The MySQL server no longer creates FRM files, ever. The server stores table meta-data in the data dictionary tables which use the InnoDB storage engine. For more details on the schema

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Today is the day in which MyISAM is no longer needed
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Of course, this is just a catchy title. As far as I know not all system tables can be converted to InnoDB yet (e.g. grant tables), which makes the header technically false. MyISAM is a very simple engine, and that has some inherent advantages (no transactional overhead, easier to “edit” manually, usually less space footprint on disk), but also some very ugly disadvantages: not crash safe, no foreign keys, only full-table locks, consistency problems, bugs in for large tables,… The 5.7.5 “Milestone 15″ release, presented today at the Oracle Open World has

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More then 1000 columns – get transactional with TokuDB
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Recently I encountered a specific situation in which a customer was forced to stay with the MyISAM engine due to a legacy application using tables with over 1000 columns. Unfortunately InnoDB has a limit at this point. I did not expect to hear this argument for MyISAM. It is usually about full text search or spatial indexes functionality that were missing in InnoDB, and which were introduced in MySQL 5.6 and 5.7, respectively, to let people forget about MyISAM. In this case though, InnoDB still could not be used, so I gave the TokuDB a

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The MySQL 5.7.5 Milestone Release is Available
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The MySQL Development team is happy to announce our 5.7.5 development milestone release (DMR), now available for download at dev.mysql.com.  You can find the full list of changes and bug fixes in the 5.7.5 release notes.  Here are the highlights. Enjoy!

Scalability

Improve scalability by not using thr_lock locks for InnoDB tables (WL#6671) : This work by Dmitry Lenev improves InnoDB scalability by not using thr_lock locks for InnoDB tables. For InnoDB tables we now rely on MDL + InnoDB row locks. This patch shows good performance/scalability improvements in the single table

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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
+0 Vote Up -0Vote Down

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,

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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

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Showing entries 1 to 10 of 764 10 Older Entries

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