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Displaying posts with tag: bugs (reset)
MySQL 8.0 GA: Quality or Not?

What does Anton Ego – a fictional restaurant critic from the Pixar movie Ratatouille – have to do with MySQL 8.0 GA?

When it comes to being a software critic, a lot.

In many ways, the work of a software critic is easy. We risk very little and thrive on negative criticism, which is fun to read and write.

But what about those who give their many hours of code development, and those who have tested such code before release? How about the many people behind the scenes who brought together packaging, documentation, multiple hours of design, marketing, online resources and more?

And all of that, I might add, is open source! Free for the world to take, copy, adapt and even incorporate in full or in part into their own open development.

It is in exactly that area that the …

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MySQL adjustment bureau


When maintainng any piece of software, we usually deal with two kind of actions:

  • bug fixing,
  • new features.

bugs and features

A bug happens when there is an error in the software, which does not behave according to the documentation or the specifications. In short, it's a breech of contract between the software maintainer and the users. The promise, i.e. the software API that was published at every major version, is broken, and the software must be reconciled with the expectations and fixed, so that it behaves again as the documentation says. When we fix a bug in this way, we increment the revision number of the software version (e.g. 1.0.0 to 1.0.1. See semantic …

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Some bugs and spring pilgrimage to Percona Live Santa Clara 2018

I am now in an airport, waiting for one of the four flights that will bring me to Percona Live Santa Clara 2018.  This is a good time to write some details about my tutorial on parallel replication.  But before talking about Percona Live, I will share thoughts on MySQL/MariaDB bugs that caught my attention in the last weeks/months (Valeriy: you clearly have an influence on me).

MySQL/MariaDB

Updates to Percona Bug Tracking

We’re completing our move of Percona bug tracking into JIRA, and the drop-dead date is December 28, 2017.

For some time now, Percona has maintained both the legacy Launchpad bug tracking system and a JIRA bug tracking system for some of the newer products. The time has come to consolidate everything into the JIRA bug tracking system.

Assuming everything goes according to schedule, on December 28, 2017, we will copy all bug reports in Launchpad into the appropriate JIRA projects (with the appropriate issue state). The new JIRA issue will link to the original Launchpad issue, and the new JIRA issue link is added to the original Launchpad issue. Once this is done, we will then turn off editing on the Launchpad projects.

Q&A Which Launchpad projects are affected?

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Revisiting roles in MySQL 8.0

In my previous article about roles I said that one of the problems with role usage is that roles need to be activated before they kick in. Let's recap briefly what the problem is:

## new session, as user `root`

mysql [localhost] {root} ((none)) > create role viewer;
Query OK, 0 rows affected (0.01 sec)

mysql [localhost] {root} ((none)) > grant select on *.* to viewer;
Query OK, 0 rows affected (0.01 sec)

mysql [localhost] {root} ((none)) > create user see_it_all identified by 'msandbox';
Query OK, 0 rows affected (0.01 sec)

mysql [localhost] {root} ((none)) > grant viewer to see_it_all;
Query OK, 0 rows affected (0.01 sec)

## NEW session, as user `see_it_all`

mysql [localhost] {see_it_all} ((none)) > use test
ERROR 1044 (42000): Access denied for user …
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How to break MySQL InnoDB cluster

A few weeks ago I started experimenting with MySQL InnoDB cluster. As part of the testing, I tried to kill a node to see what happens to the cluster.

The good news is that the cluster is resilient. When the primary node goes missing, the cluster replaces it immediately, and operations continue. This is one of the features of an High Availability system, but this feature alone does not define the usefulness or the robustness of the system. In one of my previous jobs, I worked at testing a commercial HA system and I've learned a few things about what makes a reliable system.

Armed with this knowledge, I did some more experiments with InnoDB Cluster. The attempt from my previous article had no other expectation than seeing operations continue with ease (primary node …

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MySQL super_read_only Bugs

This blog we describe an issue with MySQL 5.7’s super_read_only feature when used alongside with GTID in chained slave instances.

Background

In MySQL 5.7.5 and onward introduced the gtid_executed table in the MySQL database to store every GTID. This allows slave instances to use the GTID feature regardless whether the binlog option is set or not. Here is an example of the rows in the gtid_executed table:

mysql> SELECT * FROM mysql.gtid_executed;
+--------------------------------------+----------------+--------------+
| source_uuid                          | interval_start | interval_end | …
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When MySQL Lies: Wrong seconds_behind_master with slave_parallel_workers > 0

In today’s blog, I will show an issue with seconds_behind_master that one of our clients faced when running slave_parallel_works > 0. We found out that the reported seconds_behind_master from SHOW SLAVE STATUS was lying. To be more specific, I’m talking about bugs #84415 and #1654091.

The Issue

MySQL will not report the correct slave lag if you have slave_parallel_workers> 0. Let’s show it in practice.

I’ll use MySQL Sandbox to speed up one master and two slaves on MySQL version …

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RocksDB doesn't support large transactions very well

So I tried to do my first set of benchmarks and testing on RocksDB today, but I ran into a problem and had to file a bug:
https://github.com/facebook/mysql-5.6/issues/365

MySQL @ Facebook RocksDB appears to store at least 2x the size of the volume of changes in a transaction. I don't know how much space for the row + overhead there is in each transcation, so I'm just going to say 2x the raw size of the data changed in the transaction, as approximation. I am not sure how this works for updates either, that is whether old/new row information is maintained. If old/row data is maintained, then a pure update workload you would need 4x the ram for the given transactional changes. My bulk load was 12GB of raw data, so it failed as I have only 12GB of RAM in my test system.

The workaround (as suggested in the bug) is to set two configuration …

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RocksDB doesn't support large transactions very well

So I tried to do my first set of benchmarks and testing on RocksDB today, but I ran into a problem and had to file a bug:
https://github.com/facebook/mysql-5.6/issues/365

MySQL @ Facebook RocksDB appears to store at least 2x the size of the volume of changes in a transaction. I don't know how much space for the row + overhead there is in each transcation, so I'm just going to say 2x the raw size of the data changed in the transaction, as approximation. I am not sure how this works for updates either, that is whether old/new row information is maintained. If old/row data is maintained, then a pure update workload you would need 4x the ram for the given transactional changes. My bulk load was 12GB of raw data, so it failed as I have only 12GB of RAM in my test system.

The workaround (as suggested in the bug) is to set two configuration …

[Read more]
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