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
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 …
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
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 …[Read more]
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 …[Read more]
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 …[Read more]
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:
> 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 …[Read more]
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 …
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 …[Read more]
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 …