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Displaying posts with tag: innodb (reset)
Simulating InnoDB Secondary Index Corruption

Working as a support engineer here at Percona is amazing, as you get a variety of requests, ranging from the most trivial questions to questions that require source code review and understanding of the internals of InnoDB, for example.

In our world where High Availability is a must, everything is about being pro-active, and when we need to be reactive we must act fast. To do so we need to ensure we have proper monitoring in place that covers all possible failure scenarios. Unfortunately, that is not always possible and we are always improving and learning as we face new types of issues.

A few days ago one of our customers faced an issue where MySQL identified an InnoDB secondary index corruption and marked that table as corrupted instead of crashing the server. Even though one would think that a single table marked as …

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Fun with Bugs #89 - On MySQL Bug Reports I am Subscribed to, Part XXIII

I have to celebrate the anniversary of my last day in Oracle (that was 7 years ago!) somehow, and I think writing yet another blog post about Oracle MySQL bugs is a good way to do this. I am actually surprised (and happy) that public bugs database is still alive, maintained and considered important in Oracle, and I know who in Oracle was working hard all these years for this to happen!

In my previous post in this series I've stopped on Bug #95954 and had not completed review of interesting MySQL bug reports that I've subscribed to in June 2019. So, below I start with the next bug in my list, complete review for June and cover some bugs reported in July. There were many.

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READ ONLY transactions in MySQL

MySQL transactions can be read only. Here's how to use them, and why they are useful.

MySQL 8.0 Flow Control in Group Replication

We are well aware that MySQL Group Replication is one of the faster evolving clustering Technology for MySQL. Flow Control plays a key factor in Group Replication performance and data integrity . In this blog I am going to explain about the Flow Control mechanism and How it has evolved in MySQL 8 ?

What is Flow Control ?

MySQL Group Replication / Native Async replication needs binary logs to get the data flow across the servers.

What makes the difference ?

In the MySQL Group Replication we are trying to achieve the Synchronous replication with the help of a Flow Control mechanism and transaction acknowledgments ( certification ).

Without Flow Control, the MySQL Group Replication is asynchronous replication ? Yes, consistency is lost.

Lets us consider

We have three nodes ( GR1, GR2, GR3 ) . Gr1 is the master and and other two servers ( GR2, GR3 ) are the …

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4th Mydbops Database Meetup

Partnering to participate knowledge sharing for the community of Database Administrators.

In continuation to the community contribution with knowledge gained out of experience and networking, Mydbops IT Solutions, conducted its 4th Database Meetup on Saturday, 3rd of August, 2019. Here was the first time, that we had changed our venue. With the like-minded sponsor in M/s.Zenefits Technologies India Pvt. Ltd. They played a role of a perfect host for all of us as attendees. Their venue was a perfectly equipped to suit the knowledge sharing exercise.

Key note by Mr.Ramesh Aithal, Head of Engineering at Zenefits was build on statistics, of how the Industry is taking shape and the galore of opportunities in the coming days. The attendees from multiple companies were a great …

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Fun with Bugs #88 - On MySQL Bug Reports I am Subscribed to, Part XXII

It's Saturday night. I have a week of vacation ahead that I am going to spend at home, working on things I usually do not have time for. I already did something useful (created a couple of test cases for MariaDB bugs here and there, among other things), so why not to get some fun and continue my previous review of recent interesting MySQL bug report...

So, here is the list of 15 more MySQL community bug reports that I've subscribed to back in May and June 2019:

  • Bug #95491 - "The unused wake up in simulator AIO of function reserve_slot". I am impressed by …
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Why MySQL tables need a primary key

In MySQL and MariaDB, all tables should have a primary key - especially InnoDB tables - this is almost common wisdom. But why? Let's discuss the reasons.

Fun with Bugs #87 - On MySQL Bug Reports I am Subscribed to, Part XXI

After a 3 months long break I'd like to continue reviewing MySQL bug reports that I am subscribed to. This issue is devoted to bug reports I've considered interesting to follow in May, 2019:

  • Bug #95215 - "Memory lifetime of variables between check and update incorrectly managed". As demonstrated by Manuel Ung, there is a problem with all InnoDB MYSQL_SYSVAR_STR variables that can be dynamically updated. Valgrind allows to highlight it.
  • Bug #95218 - "Virtual generated column altered …
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Fun with Bugs #86 - On Some Public Bugs Fixed in MySQL 5.7.27

This week new minor releases of MySQL server were announced. Of them all I am mostly interested in MySQL 5.7.27. I plan to concentrate on InnoDB, replication and optimizer bugs reported in public MySQL bugs database and fixed in MySQL 5.7.27. As usual I name bug reporters explicitly and give links to their remaining currently active bug reports, if any.

Let me start with InnoDB bug fixes:

  • Bug #94699 - "Mysql deadlock and bugcheck on aarch64 under stress test". This bug report with a fix for insufficient memory barriers in the rw-lock implementation was contributed by Cai Yibo.
  • Bug #93708 - "Page Cleaner will sleep for long …
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MySQL 8.0.17 Release and The Clone Plugin

MySQL 8.0.17 is officially released Yesterday. The most talked feature is the clone plugin, which enables the automatic node provisioning from an existing node (a Donor). This also closes the gap between MySQL Group Replication and Galera Cluster on usability.

Congrats to MySQL engineering team on the excellent work! Specially expose the visibility of the operations:

mysql> SELECT STATE FROM performance_schema.clone_status;
+-----------+
| STATE     |
+-----------+
| Completed |
+-----------+
1 row in set (0.02 sec)

mysql> SELECT STAGE, STATE, END_TIME FROM performance_schema.clone_progress;
+-----------+-------------+----------------------------+
| STAGE     | STATE       | END_TIME      …

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