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Displaying posts with tag: speculations (reset)
Fun with Bugs #67 - On Some Public Bugs Fixed in MySQL 8.0.11 GA

I stopped reviewing MySQL Release Notes for quite a some time, but major GA releases of MySQL do not happen often, so I decided to make an exception and write about some bugs from Community users fixed in MySQL 8.0.11 GA.

I'll start with good news about MySQL 8.0.11 GA! You can get sources at GitHub, and I had no problems to build on Fedora 27 on my good old QuadCore box, using the following cmake command line:
[openxs@fc23 mysql-server]$ cmake . -DCMAKE_BUILD_TYPE=RelWithDebInfo -DBUILD_CONFIG=mysql_release -DFEATURE_SET=community -DWITH_EMBEDDED_SERVER=OFF -DDOWNLOAD_BOOST=1 -DWITH_BOOST=/home/openxs/boost …

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Fun with Bugs #66 - On MySQL Bug Reports I am Subscribed to, Part VI

I have some free time today, but I am still lazy enough to work on numerous planned and pending "ToDo" kind of posts, so why not to continue review of older MySQL bugs I am subscribed to. Today I am going to list 15 more bugs reported more than a year ago and still not fixed:

  • Bug #85805 - "Incorrect ER_BAD_NULL_ERROR after LOAD DATA LOCAL INFILE". This detailed bug report by Tsubasa Tanaka stays "Verified" for more than a year already. It's a great example of gdb use for MySQL troubleshooting. Setting a couple of breakpoints may really help to understand how MySQL works and why some …
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Fun with Bugs #65 - On MySQL Bug Reports I am Subscribed to, Part V

I think it's time to review some bugs I've subscribed to several months ago, those older than in the first post from this series. There are several really serious bugs in the list of 15 below:

  • Bug #87560 - "XA PREPARE log order error in replication and binlog recovery". This bug was reported by Wei Zhao, who also provided patches.
  • Bug #87526 - "The output of 'XA recover convert xid' is not useful". This bug reported by Sveta Smirnova is well known and is a real pain for DBAs who have to deal with incomplete XA transactions after some crash or unexpected restart. Check  …
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Fun with Bugs #64 - On MySQL Bug Reports I am Subscribed to, Part IV

I've subscribed to more than 15 new MySQL bug reports since the previous post in this series, so it's time for a new one. I am trying to follow important, funny or hard to process bug reports every day. Here is the list of the most interesting recent ones starting from the latest (with several still not processed properly):

  • Bug #90211 - "Various warnings and errors when compiling MySQL 8 with Clang".  Roel Van de Paar and Percona in general continue their QA efforts in a hope to make MySQL 8 better. Current opinion of Oracle …
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Windows Tools for MySQL DBAs: Basic Minidump Analysis

"To a man with a hammer, everything looks like a nail."Even though I had written many posts explaining the use of gdb for various MySQL-related tasks, I have to use other OS level troubleshooting tools from time to time. Moreover, as MySQL and MariaDB are still supported and used under Microsoft Windows in production by customers I have to serve them there, and use Windows-specific tools sometimes. So, I decided to start a series of posts (that I promised to my great colleague Vladislav Vaintroub (a.k.a Wlad) who helped me a lot over years and actually switched my attention from Performance Schema towards debuggers) about different Windows tools for MySQL DBAs (and support engineers).

Developers (and maybe even power users) on Windows probably know …

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Fun with Bugs #63 - On Bugs Detected by ASan

Among other things Geir Hoydalsvik stated in his nice post yesterday:
 "We’ve fixed a number of bugs detected by UBsan and Asan." This is indeed true, I already noted many related bugs fixed in recent MySQL 8.0.4. But I think that a couple of details are missing in the blog post. First of all, there still a notable number of bugs detected by ASan or noted in builds with ASan that remain "Verified". Second, who actually found and reported these bugs?

I decided to do a quick search and present my summary to clarify these details. Let me start with the list of "Verified" or "Open" bugs in public MySQL bugs database, starting from the oldest one:

  • Bug #69715 - "UBSAN: Item_func_mul::int_op() mishandles …
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Fun With Bugs #62 - On Bugs Related to JSON Support in MySQL

Comparing to "online ALTER" or FULLTEXT indexes in InnoDB, I am not that much exposed to using JSON in MySQL. OK, there is EXPLAIN ... FORMAT=JSON statement that is quite useful, optimizer trace in MySQL is also in JSON format, but otherwise I rarely have to even read this kind of data since my lame attempt to pass one introductory MongoDB training couse back in 2015 (when I mostly enjoyed mongo shell). Even less I care about storing JSON in MySQL.

But it …

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Checking User Threads With gdb in MySQL 5.7+

In one of my gdb-related posts last year I noted that there is no more simple global list of user threads in MySQL 5.7+:
"I had highlighted Global_THD_manager singleton also as during my next gdb sessions I had found out that simple global list of threads is also gone and in 5.7 everything is done via that Global_THD_manager. This is a topic for some other post, though."In that post and many times later when I had to deal with MySQL 5.7+ I just checked OS threads one by one in gdb using thread  1 ... thread N commands. This is not efficient at best, as I also hit numerous background threads that I often do not care about. So, a couple of weeks ago I finally decided to get back to this topic and find out how to check just user threads one by one in recent MySQL versions. I had a nice …

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On InnoDB's FULLTEXT Indexes

I had recently written about InnoDB features that I try to avoid by all means if not hate: "online" DDL and persistent optimizer statistics. Time to add one more to the list - FULLTEXT indexes.

This feature had a lot of problems when initially introduced in MySQL 5.6. There was a nice series of blog posts about the initial experience with it by my colleague from Percona (at that times) Ernie Souhrada: part I, …

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Fun with Bugs #61 - On MySQL Bug Reports I am Subscribed to, Part III

Since my previous post on this topic I've subscribed to 19 more MySQL bugs, so it's time for yet another review of these reports. I am trying to pick up important, funny or hard to process reports every day, and here is the list of the most interesting ones starting from the latest:

  • Bug #89607 - "MySQL crash in debug, PFS thread not handling singals." We have a patch contributed by Robert Golebiowski.
  • Bug #89583 - "no rpm build instructions from source git tree". As Simon Mudd put it:
    "... The sources are supposed to be in the git tree …
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