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Displaying posts with tag: bugs (reset)
On New Severity Levels for MySQL Bugs

Four weeks ago while working on a blog post about half baked XA transactions feature of MySQL server I've noted that there are new severity levels added by Oracle for MySQL bug reports. Previously we had 5 levels:

  • S1 (Critical) - mostly for all kinds of crashes, DoS attack vectors, data corruptions etc
  • S2 (Serious) - mostly for wrong results bugs, broken replication etc
  • S3 (Non-critical) - all kinds of minor but annoying bugs, from unexpected results in some corner cases to misleading or wrong error messages, inefficient or unclear code etc
  • S4 (Feature requests) - anything that should work or be implemented based on common sense, but is not documented in the manual and was not required by the original specification or implementation of some feature.
  • S5 (Performance) - …
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Fun with Bugs #71 - On Some Public Bugs Fixed in MySQL 5.7.24

Oracle released many new MySQL versions back on Monday, but I had no time during this very busy week to check anything related (besides the fact that MySQL 8.0.13 can be complied from source on my Fedora 27 box). I am sure you've read a lot about MySQL 8.0.13 elsewhere already, even patches contributed by Community are already presented in a separate post by Jesper Krogh.

I am still mostly interested in MySQL 5.7. So, here is my typical quick review of some selected bugs reported in public by MySQL Community users and fixed in MySQL …

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On Some Recent MySQL Optimizer Bugs

Yet another topic I missed in my blog post on problematic MySQL features back in July is MySQL optimizer. Unlike with XA transactions, it was done in purpose, as known bugs, limitations and deficiencies of MySQL optimizer is a topic for a series of blog posts if not a separate blog. At the moment the list of known active bug reports in optimize category consists of …

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On MySQL XA Transactions

One of the features I missed in my blog post on problematic MySQL features back in July is XA transactions. Probably I was too much in a hurry, as this feature is known to be somewhat buggy, limited and not widely used outside of Java applications. My first related feature request, Bug #40445 - "Provide C functions library implementing X/OPEN XA interface for Bea Tuxedo", was created almost 10 years ago, based on the issue from one of MySQL/Sun customers of that time. I remember some …

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Why Optimization derived_merge can Break Your Queries

Lately, I worked on several queries which started returning wrong results after upgrading MySQL Server to version 5.7 The reason for the failure was derived merge optimization which is one of the default

optimizer_switch

  options. Issues were solved, though at the price of performance, when we turned it

OFF

 . But, more importantly, we could not predict if any other query would start returning incorrect data, to allow us to fix the application before it was too late. Therefore I tried to find reasons why

derived_merge

  can fail. Analyzing the problem

In the first run, we turned SQL Mode

ONLY_FULL_GROUP_BY

on, and this removed most of the problematic queries. That said, few of the queries that were successfully working with

ONLY_FULL_GROUP_BY

  were affected.

A quick search in the …

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On MySQL Replication Bugs

While writing about problematic Oracle MySQL features previously I concentrated mostly on InnoDB problems that I have to fight with really often and deliberately skipped replication from even the preliminary list of features to study in details for that blog post. First of all, I mostly work with MariaDB users now, and implementation of many replication features in MariaDB is notably different already (and has its own list of known problems). But this happened also because (asynchronous) replication plays a key role in most MySQL environments and deserves a detailed study in a separate post.

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On Fine MySQL Manual

Today I am going to provide some details on the last item in my list of problems with Oracle's way of MySQL server development, maintenance of MySQL Manual. I stated that:
"MySQL Manual still have many details missing and is not fixed fast enough.
Moreover, it is not open source...
"Let me explain the above:

  1. MySQL Reference Manual is not open source. It used to be built from DocBook XML sources. Probably that's still the case. But you can not find the source code in open repositories (please, correct me if I am wrong, I tried to search...) That's because it is NOT open source. It says this clearly in …
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On Oracle's QA for MySQL

In my recent blog posts I presented lists of bugs, fixed and not yet fixed, as usual. Working on these lists side tracked me from the main topic of this summer - problems in Oracle's way of handling MySQL. Time to get back on track!

Among things Oracle could do better for MySQL I mentioned QA:
"Oracle's internal QA efforts still seem to be somewhat limited.
We get regression bugs, ASAN failures, debug assertions, crashes, test failures etc in the official releases, and Oracle MySQL still …

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Fun with Bugs #70 - On MySQL Bug Reports I am Subscribed to, Part VIII

More than 2 months passed since my previous review of active MySQL bug reports I am subscribed to, so it's time to describe what I was interested in this summer.

Let's start with few bug reports that really surprised me:

  • Bug #91893 - "LOAD DATA INFILE throws error with NOT NULL column defined via SET". The bug was reported yesterday and seem to be about a regression in MySQL 8.0.12 vs older versions. At least I have no problem to use such a way to generate columns for LOAD DATA with MariaDB 10.3.7.
  • Bug #91847 - "Assertion `thread_ids.empty()' failed.". As usual, Roel Van de Paar
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Fun with Bugs #69 - On Some Public Bugs Fixed in MySQL 5.7.23

Several MySQL releases happened yesterday, but of them all I am mostly interested in MySQL 5.7.23, as MySQL 5.7 (either directly or indirectly, via forks and upstream fixes they merge) is probably the most widely used MySQL GA release at the moment.

In this post (in a typical manner for this "Fun with Bugs" series)  I'd like to describe several bugs reported by MySQL Community users and fixed in MySQL 5.7.23. As usual, I'll try to concentrate mostly on InnoDB, replication, partitioning and optimizer-related bugs (if any).

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