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Displaying posts with tag: innodb (reset)
Backup and Restore of Encrypted Innodb Tables


Fun with Bugs #44 - Community Bugs Fixed in MySQL 5.7.14

MySQL 5.7.14 was officially released yesterday. So, it's time to check what bugs reported by MySQL Community in public were fixed in this release. Some of these bugs are presented below.

As usual, let me start with InnoDB. The following bugs were fixed there:

  • Bug #80296 - "FTS query exceeds result cache limit". It was reported (for 5.6, but I do not see new 5.6 release notes yet) by Monty Solomon and verified by Umesh.
  • Bug #80304 - "generated columns don't work with foreign key actions". It was reported by Guilhem Bichot based on test case by Peter Gulutzan presented …
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Understanding Bulk Index Creation in InnoDB (and innodb_sort_buffer_size)

In a previous post, I presented an Unexpected Memory Consumption for Bulk Index Creation in InnoDB.  This was triggered by an increased innodb_sort_buffer_size and as stated in another post: "the sorting algorithm does not scale well with large sort buffers".  In this post, I will present why it does not scale well and I will suggest solutions.

This post also answers feedback request for the

Percona Server 5.6.31-77.0 is now available


Percona
 announces the release of Percona Server 5.6.31-77.0 on July 7th, 2016. Download the latest version from the Percona web site or the Percona Software Repositories.

Based on MySQL 5.6.31, including all the bug fixes in it, Percona Server 5.6.31-77.0 is the current GA release in the Percona Server 5.6 series. Percona Server is open-source and free …

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Percona Server 5.7.13-6 is now available

Percona announces the GA release of Percona Server 5.7.13-6 on July 6, 2016. Download the latest version from the Percona web site or from the Percona Software Repositories.

Based on MySQL 5.7.13, including all the bug fixes in it, Percona Server 5.7.13-6 is the current GA release in the Percona Server 5.7 series. Percona’s provides completely open-source and free software. All the details of the release can be found in the …

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Q: Does MySQL support ACID? A: Yes

I was recently asked this question by an experienced academic at the NY Oracle Users Group event I presented at.

Does MySQL support ACID? (ACID is a set of properties essential for a relational database to perform transactions, i.e. a discrete unit of work.)

Yes, MySQL fully supports ACID, that is Atomicity, Consistency, Isolation and Duration. (*)

This is contrary to the first Google response found searching this question which for reference states “The standard table handler for MySQL is not ACID compliant because it doesn’t support consistency, isolation, or durability”.

The question is however not a simple Yes/No because it depends on timing …

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InnoDB locks and transaction isolation level

What is the difference between InnoDB locks and transaction isolation level? We’ll discuss it in this post.

Recently I received a question from a user about one of my earlier blog posts. Since it wasn’t sent as a comment, I will answer it here. The question:

> I am reading your article:
> https://www.percona.com/resources/technical-presentations/troubleshooting-locking-issues-percona-mysql-webinar

> Full table scan locks whole table.

> Some bad select (read) query can do full table scan on InnoDB, does it lock whole table please?

> My understanding was that SELECT (read) blocks another DML only in MyISAM.

To answer this question, we to need understand two different concepts: locking and …

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Fun with Bugs #43 - Bugs Fixed in MySQL 5.7.13

For some reason I do not see numerous public announcements about recent MySQL 5.7.13 release, even though it happened a couple of days ago formally. Maybe that's because we do not have any really "big" new features in this release (new ->> operator for introduced though for those who, unlike me, care about JSON). Still there are many fixes for bugs previously reported by Community (or Oracle engineers, but still in public bugs database), and I'd like to discuss some of them.

Let me start with the bug that was NOT fixed though, Bug #81093, "mysqld_multi not included in mysql-community-server package", reported by Georgi Iovchev and …

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Percona Server 5.7: multi-threaded LRU flushing

In this blog post, we’ll discuss how to use multi-threaded LRU flushing to prevent bottlenecks in MySQL.

In the previous post, we saw that InnoDB 5.7 performs a lot of single-page LRU flushes, which in turn are serialized by the shared doublewrite buffer. Based on our 5.6 experience we have decided to attack the single-page flush issue first.

Let’s start with describing a single-page flush. If the working set of a database instance is bigger than the available buffer pool, existing data pages will have to be evicted or flushed (and then evicted) to make room for queries reading in new pages. InnoDB tries to anticipate this by maintaining a list of free pages per buffer pool instance; these are the pages that can be immediately used for placing the newly-read data pages. The target length of the free page list is governed by the …

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Fun with Bugs #42 - Bugs Fixed in MySQL 5.7.12

MySQL 5.7.12 was released more than 2 weeks ago. New features introduced there in a form of "rapid plugins" are widely discussed, but I am more interested in bugs reported by MySQL Community users that are fixed there. Unfortunately I do not see MySQL Community Release Notes by Morgan (like this) for quite a some time, so I have to continue describing key bug fixes and name people who reported and verified bugs in my "Fun with Bugs" series.

As usual, let's start with InnoDB bugs fixed:

  • Bug #80070 - "allocated_size and file_size differ if create general tablespace outside datadir". It was reported by my former colleague from Percona …
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