This document discusses how to create useful bug reports for MySQL. It emphasizes searching existing reports before reporting, providing all necessary details to reproduce the bug, and using tools to simplify test cases. Examples are given of both useful reports that were addressed and useless ones that lacked important information. Escalating important bugs is also covered.

1. How to Create a Useful
MySQL Bug Report
Valerii Kravchuk, Principal Support Engineer
valerii.kravchuk@percona.com

2. www.percona.com
Who am I?
Valerii (aka Valeriy) Kravchuk:
● MySQL Support Engineer in MySQL AB, Sun and Oracle, 2005 - 2012
○ Bugs Verification Team all this time
○ Support issues related to bugs, InnoDB, performance...
○ Trainings (mostly informal) for new team members
○ All kinds of decision making committees…
● Principal Support Engineer in Percona since September, 2012
○ Doing more or less the same as before, but better (I hope)...
○ Plus I try to speak and write about MySQL in public now
● http://mysqlentomologist.blogspot.com - my blog about MySQL (mostly bugs)
● https://www.facebook.com/valerii.kravchuk - my Facebook page, a lot about
MySQL (mostly bugs…)
● http://bugs.mysql.com - my personal playground. 88 bugs reported in 2014

3. www.percona.com
What is this session about?
● Report MySQL bugs at http://bugs.mysql.com (or other
public tracker)!
● What is a “Useful MySQL Bug Report”?
● What to do before reporting a bug?
● How to search for known MySQL bugs efficiently?
● What tools may help to create a useful bug report?
● Life cycle of Oracle/MySQL public bug report
● Life cycle of Percona bug report
● Examples of useful bug reports
● Examples of useless bug reports
● How to escalate bug reports?

4. www.percona.com
Report bugs in public!
● Why? I am customer! http://mysqlentomologist.blogspot.com/2012/12/new-year-wishes-
for-customers-of.html:
○ easy to search for: site:bugs.mysql.com drop add index InnoDB
○ becomes visible to other customers, community members and MySQL support providers and
developers outside of Oracle
● http://bugs.mysql.com - MySQL software from Oracle
● https://mariadb.atlassian.net/browse/MDEV - MariaDB
● https://bugs.launchpad.net/percona-server
● https://bugs.launchpad.net/percona-xtradb-cluster
● https://bugs.launchpad.net/percona-xtrabackup
● https://bugs.launchpad.net/percona-toolkit

5. Features of a Useful Bug Report
● It’s a real, new bug that was never reported before (or
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was once fixed but now appeared again)
● It’s clear what the bug is and how to reproduce it
● Bug reporter cared to check on latest officially released
version in the branch
● All important details about the environment and impact
are provided
● It’s clear that bug reporter spent enough efforts on it
(search, testing, attempts to provide a minimal test case)
● Anything wrong or missed in the above?

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Before you report a bug...
● Try to find similar bugs (bug tracker specific search,
Google, ...)
● Try to find a solution/reason by reading the manual
● Try to reproduce the bug in “clean environment”
● Make sure you’ve read vendor-specific (and product
specific, if any) instructions:
https://mariadb.com/kb/en/mariadb/development/debugging-mariadb/reporting-bugs/
http://bugs.mysql.com/how-to-report.php
http://mysqlworkbench.org/faq/faq-bugreporting/
● Make sure you’ve read this entirely at least once:
http://www.catb.org/esr/faqs/smart-questions.html

7. How to search for known bugs?
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● Use Google like this:
site:bugs.mysql.com drop table slow
and check at least first 3 pages of results and links there
● Search for specific error messages, lines from stack trace,
versions, filenames and line numbers, names
● Do not ignore bug tracker specific search:
○ Specific categories
○ Bugs vs. Feature requests
○ Specific version, bug status etc
● Study features and limitations of your search tools
● Keep your own notes and test cases “database”

8. www.percona.com
Tools for bug reporters
● Randgen (RQG)
○ http://www.percona.com/blog/2014/04/17/how-to-find-bugs-in-mysql/
● MTR (MySQL regression test suite)
○ http://dev.mysql.com/doc/refman/5.6/en/mysql-test-suite.html
● reducer.sh:
○ http://www.percona.com/blog/2014/09/03/reducer-sh-a-powerful-mysql-test-case-simplificationreducer-
tool/
● MySQL Sandbox
● Percona Toolkit (pt-summary, pt-mysql-summary, more)
● Debug binaries and trace
● Valgrind and Massif:
○ http://www.percona.com/blog/2013/01/09/profiling-mysql-memory-usage-with-valgrind-massif/
● Anything else?

9. www.percona.com
Life Cycle of MySQL Bug
http://mysqlentomologist.blogspot.com/2013/01/life-cycle-of-mysql-bug.html
● Open
● Analyzing
● Need Feedback → No Feedback (expires in 30 days)
● Can’t repeat
● Verified
● Not a Bug
● Duplicate
● Unsupported
● Won’t fix
● In progress… (real progress happens elsewhere)
● Closed
● What about feature requests?

10. Life Cycle of Percona (launchpad) Bug
● New (“Open”), no automatic re-opening on new comment
● Incomplete (“Need Feedback”), expires in 60 days
● Invalid (“Not a bug”, “Can’t repeat”)
● Confirmed (“Verified”)
● Triaged
● In progress
● Fix committed
● Fix released (“Closed”)
● Won’t Fix
● Separate status per branch (5.5/5.6) and project
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(PS/PXC), also upstream references...

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Examples: useful bug reports
● http://bugs.mysql.com/bug.php?id=69979 - how repeatable read works (NaB)
● http://bugs.mysql.com/bug.php?id=73837 - how to report optimizer bugs
● http://bugs.mysql.com/bug.php?id=68705 - Valgrind in use to find memory leak
● http://bugs.mysql.com/bug.php?id=73825 - simple wrong results bug
● http://bugs.mysql.com/bug.php?id=73881 - RQG in action
● http://bugs.mysql.com/bug.php?id=68554 - optimizer trace, level of details
● http://bugs.mysql.com/bug.php?id=68079 - sysbench, P_S, cooperation
● http://bugs.mysql.com/bug.php?id=69253 - with patch suggested (mind OCA)
● http://bugs.mysql.com/bug.php?id=73018 - even good reports may stay Open
● ...

12. www.percona.com
Examples: useless bug reports
● http://bugs.mysql.com/bug.php?id=2 - pure fun. Not fixed for 12 years!
● http://bugs.mysql.com/bug.php?id=69878 - real bug, but many problems
reported in one, no respect
● http://bugs.mysql.com/bug.php?id=55796 - “it really sucks”, gotcha...
● http://bugs.mysql.com/bug.php?id=73960 - “this query is very slow”...
● http://bugs.mysql.com/bug.php?id=73921 - free support request, 5.5.34
● http://bugs.mysql.com/bug.php?id=73844 - almost no details, others wrong
● https://bugs.launchpad.net/percona-server/+bug/1245141 - RBR with no
PK/UK in 5.5. Time to check for known problems… Free support request
● ...

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How to escalate the bug?
● Verified (or Open but real) bug is not fixed. What to do?
○ Add comment, ask, curse, complain in report
○ Ask others to comment, use “Affects Me” button
○ Report it again?
○ Report it in other bug tracker (to other company)
○ Blog about it
○ Open issue (support request) about it
○ Ask some developer in private
○ Complain on Facebook
○ Tell me about it

14. Hall of Fame: they process your bugs!
● Umesh Shastry (Oracle, 50+% of all bugs Verified)
● Shane Bester (MySQL, Sun, Oracle)
● Sveta Smirnova (MySQL, Sun, Oracle)
● Miguel Solorzano (MySQL, Sun, Oracle)
● Elena Stepanova (Sun, Oracle, MariaDB)
● Nilnandan Joshi (PS, PXC, pt-*, PXB)
● Raghavendra Prabhu (PXC)
● Laurynas Biveinis (PS)
● Roel Van de Paar (PS, PXC) - MySQL, Sun and Oracle
● Alexey Kopytov (PXB, PS) - MySQL, Sun and Oracle
● ...
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15. Any bug reports you want to discuss?
● http://bugs.mysql.com/bug.php?id=73369 - sometimes
even experienced Support engineers have problems
● http://bugs.mysql.com/bug.php?id=69979 - even if it’s
“Not a bug” eventually, it was a useful work for all!
● http://bugs.mysql.com/bug.php?id=71095 - you can get
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patch in a matter of days!
● “Private” and “Security” bugs in public bugs databases.
Should they exist, who decides on these statuses, when
they should become public?
● Your examples?

16. www.percona.com
Thank you!
Questions and Answers
Please, report bugs at:
http://bugs.mysql.com
Use “Affects Me” button!