Feed Aggregator

I have described 3 different ways to "solve" the problem above:

• I assume MySQL has just disabled the Note?
• You can find various advices in the Internet about how to get rid of this Note:
• So I strongly assume it is a noisy-neighbour problem. ... Because we did not cause more load and over-saturated the system it must be triggered externally:

So find out, which one of the latter two will help you.

only Problem statement, where is the solution to this issue of Page Cleaners?

Repositories from your favourite Linux distribution and from your favourite database software vendor get regular package updates. If you do periodic system upgrades (for example every 2 weeks as we do) you get the newest packages of a release series.
Unfortunately recently the software vendors started not only to fix bugs in new releases but also to introduce new features. And when you fix bugs or introduce new stuff new bugs might appear.
To avoid being hit unexpectedly by new bugs you do not want to upgrade untested software. To achieve this you want to keep/not upgrade some important packages. For example the MariaDB or MySQL server package.
This package pinning is called package version lock on CentOS and Redhat and package holding on Debian and Ubuntu.

How you do this I have summarized below:

Debian / Ubuntu

See also apt_preferences (APT pinning) and man 5 apt_preferences

shell> dpkg -l | grep mariadb
ii  libmariadb3:amd64                     3.0.3-1build1                                   amd64 …

When you are for too long in business you think you know already everything and you are getting lazy. This happened to me again a few weeks ago. A customer asked me about the SQL Error Log Plugin. First I though he was talking about the MariaDB Error Log or the General Query Log. But then I have learned that there is something “new” I did not know yet…

MariaDB introduced in 5.5.22 (March 2012) a new plugin called the SQL Error Log Plugin. This Plugin collects all the errors which were sent from the MariaDB daemon to applications/clients and writes it to a log file.

This Client error log file can be analysed later to find and fix bugs in the application if the applications did not catch the errors themselves.

Installation

The Plugin can be easily installed with:

SQL> INSTALL PLUGIN sql_error_log SONAME 'sql_errlog';

and uninstalled again with:

SQL> UNINSTALL PLUGIN sql_error_log;
Query OK, 0 rows affected, 1 warning (0.002 sec)

The installation and uninstallation informations are …

With the FromDual Ops Center file transfer tool you can easily upload files from your personal computer to the focmm machine, download files from the focmm machine to your personal computer or transfer files from the focmm machine to any of your database machines or between them. This feature is made for importing, exporting or transferring data from, to or between your different database instances. For example to copy a production schema to a testing database instance.

For backup and restore of a database instance or schema see Operations.

You can reach the file transfer tool under the menu Tools on the left and then File transfer.

Upload

For uploading a file just click to the Browse… button, select a file from your local file system and then click to Upload File.

After a while, when the upload is completed, the file will appear in the Download section of your focmm machine.

Alternatively you can also upload files from your personal computer to the focmm machine via your favourite file transfer …

One of the tools of FromDual Ops Center for MariaDB and MySQL is the centralized crontab for all of your database machines. Instead of maintaining various different crontabs on different machines you can manage them now in one place within the Ops Center.

Under the Tools menu on the left you find Crontab. Here you get a first overview of crontab jobs available:

• The first column shows if the crontab job is active or not.
• The second column indicates the O/S user the crontab job should run as.
• Then we have the typical crontab scheduling entries: Minute, Hour, Day, Month and Day of Week (DoW).
• Now follows the actual command which should be run with a comment describing the command.
• The column Last indicates when the job was run last successfully.
• And RC shows the last Return Code of the job (0 - success, otherwise error number).
• With the trash icon you can delete a crontab job and with the run icon you can start and run a crontab job right now.

With the Add Crontab Entry button on the bottom you can add new …

We have found a strong correlation between VMware snapshots and Veeam backups and those dropped packets.

In a recent customer engagement we experienced a lot of corrupted (normal) indexes and also corrupted full-text indexes on InnoDB tables in a Galera Cluster (v10.4.13).

In the error log we did not see which table it was but we have only a few log entries every here and there indicating a full-table index is corrupt:

2020-07-08 22:09:03 0 [ERROR] InnoDB: (Duplicate key) writing word node to FTS auxiliary index table.
2020-07-08 22:09:06 0 [ERROR] InnoDB: (Duplicate key) writing word node to FTS auxiliary index table.
2020-07-08 22:09:09 0 [ERROR] InnoDB: (Duplicate key) writing word node to FTS auxiliary index table.

So we tried to figure out which database files were touch in the indicated time:

shell> ls -ltr */FTS_*.ibd | tail -n8
-rw-rw---- 1 mysql mysql    98304 Jul  8 22:09 test/FTS_00000000000005ee_00000000000011d3_INDEX_4.ibd
-rw-rw---- 1 mysql mysql    98304 Jul  8 22:09 test/FTS_00000000000005ee_00000000000011d3_INDEX_5.ibd
-rw-rw---- 1 mysql mysql    98304 Jul  8 22:09 …

Asking stupid questions and googling for them is fun some times…

Today I was asking myself if one could rise the file limit for a running MariaDB mysqld process online without restarting the database instance?

And I found an answer on serverfault: Set max file limit on a running process:

PID=$(pidof mysqld)

grep -e 'Max open files' -e Limit /proc/${PID}/limits 
Limit                     Soft Limit           Hard Limit           Units     
Max open files            1024                 4096                 files     

prlimit --pid $PID | grep -e NOFILE -e DESC
RESOURCE   DESCRIPTION                             SOFT      HARD UNITS
NOFILE     max number of open files                1024      4096 files

prlimit  --nofile --output RESOURCE,SOFT,HARD --pid ${PID}
RESOURCE SOFT HARD
NOFILE   1024 4096

sudo prlimit --nofile=2048:8192 --pid ${PID}

prlimit  --nofile --output RESOURCE,SOFT,HARD --pid ${PID}
RESOURCE SOFT HARD
NOFILE   2048 8192

Literature

prlimit(1)

See also:

• File Limit für MySQL hoch …

With this new version of fpmmm you probably get a new warning in your fpmmm error log:

INFO: FromDual Performance Monitor for MySQL and MariaDB (fpmmm) (1.2.0) run started.
WARN:     P_S Metadata Lock instrumentation is disabled. (rc=1411)
INFO: FromDual Performance Monitor for MySQL and MariaDB (fpmmm) run finished (rc=0).

In this fpmmm release we start monitoring MariaDB/MySQL Metadata locking problems. For this new functionality the Metadata locking plugin in MariaDB or the Metadata instrumentation in MySQL PERFORMANCE_SCHEMA must be enabled. This can be done dynamically and persistent for MariaDB:

mariadb> INSTALL SONAME 'metadata_lock_info';

and dynamically for MySQL:

mysql> UPDATE performance_schema.setup_instruments SET enabled = 'YES', timed = 'YES' WHERE name = 'wait/lock/metadata/sql/mdl';

or persistent for MySQL:

#
# my.cnf
#
performance_schema_instrument = 'wait/lock/metadata/sql/mdl=ON'

Sources:

• RSyslog Documentation
• How to Configure Remote Logging with Rsyslog on Ubuntu 18.04

This notes are intended for Ubuntu 18.04!

Install and Configure Rsyslog Server

dpkg -l | grep rsyslogd
apt-get update && apt-get install rsyslog

systemctl start rsyslog
systemctl enable rsyslog
systemctl status rsyslog

Check rsyslog version (v7 vs. v8!):

rsyslogd -v

General configuration

#
# /etc/rsyslog.conf
#

# provides UDP syslog reception
module(load="imudp")
input(type="imudp" port="514")

and/or

# provides TCP syslog reception
module(load="imtcp")
# RPC service is using this port as well.
input(type="imtcp" port="50514")

Restrictions:

# GLOBAL DIRECTIVES

$AllowedSender UDP, 192.168.1.0/24, [::1]/128, *.fromdual.com
$AllowedSender UDP, 192.168.56.0/24, [::1]/128, *.fromdual.com

$AllowedSender TCP, 192.168.1.0/24, [::1]/128, *.fromdual.com
$AllowedSender TCP, 192.168.56.0/24, [::1]/128, *.fromdual.com

Specific configuration:

#
# …

FromDual has the pleasure to announce the release of the new version 1.2.0 of its popular Database Performance Monitor for MariaDB and Galera Cluster fpmmm.

The FromDual Performance Monitor for MariaDB (fpmmm) enables DBAs and System Administrators to monitor and understand what is going on inside their MariaDB database instances and on the machines where the databases reside.

More detailed information you can find in the fpmmm Installation Guide.

Download

The new FromDual Performance Monitor for MariaDB (fpmmm) can be downloaded from here or you can use our FromDual repositories. How to install and use fpmmm is documented in the fpmmm Installation Guide.

In the inconceivable case that you find a bug in the FromDual Performance Monitor for MariaDB please report it to the FromDual Bug-tracker or just send us an [email](mailto:contact@fromdual.com?Subject=Bug report for fpmmm).

Any feedback, statements and testimonials are welcome as well! Please send them [to us](mailto:feedback@fromdual.com?Subject=Feedback …

Trx # 86153878218 exists in both Galera Cluster conflics which are 46 seconds apart (= long running transaction?). Table `rt3`.`Tickets` seems to be involved in both cases. One should investigate also in this query or transaction we cannot see here...

MySQL thread id 6147, OS thread handle 0x7f5af77fe700, query id 5394536 192.168.1.42 node1
*** WAITING FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 67799 page no 2924419 n bits 136 index `PRIMARY` of table `rt3`.`Tickets` trx id 86153787673 lock_mode X locks rec but not gap
2020-06-09 08:27:24 9737 [Note] WSREP: cluster conflict due to high priority abort for threads:
2020-06-09 08:27:24 9737 [Note] WSREP: Winning thread:
   THD: 26, mode: applier, state: executing, conflict: no conflict, seqno: 1297074501
   SQL: (null)
2020-06-09 08:27:24 9737 [Note] WSREP: Victim thread:
   THD: 6147, mode: local, state: executing, conflict: no conflict, seqno: -1
   SQL: SELECT main.* FROM Attributes main  WHERE (main.ObjectId = 3137700935) AND …

Very often I see some stupid error messages as a (power-)user. I do not know if this is because of lazy developers or managers not having enough focus on more useful error messages.

If the error messages would be more clear it would help me as a power-user to fix my problems faster and fix it possibly myself instead of asking questions or even open support cases.

That would also safe costs on the support service side if end-users would be enabled to fix their problems themself. If this is what software vendors really want…

Sometimes strace helps to understand the problem. But why do I need external tools to do the job?

Some examples

Bad: Could not add A-record.

Better: Could not add A-record lamp-database.org because it already exists.

Bad: Error 2.

OK I can help myself with:

perror 2
OS error code   2:  No such file or directory

but still bad.

Better: No such file or directory. File I was looking for: /tmp/doesnotexist.txt

Unique Error Code Policy

FromDual has introduced a unique error code policy: …

FromDual has the pleasure to announce the release of the new version 1.0.0 of its popular FromDual Ops Center focmm, a Graphical User Interface (GUI) for MySQL and compatible databases.

The FromDual Ops Center for MySQL and compatible databases (focmm) helps DBA’s and System Administrators to better manage their MySQL and compatible databases farms. Ops Center makes DBA and Admins life easier!

The main task of Ops Center is to support you in your daily MySQL and compatible databases operation tasks. More information about FromDual Ops Center you can find here.

Download

The new FromDual Ops Center for MySQL and compatible databases (focmm) can be downloaded from here. How to install and use focmm is documented in the Ops Center User Guide.

In the inconceivable case that you find a bug in the FromDual Ops Center for MySQL and compatible databases please report it to the FromDual bug tracker or just send us an [email](mailto:contact@fromdual.com?Subject=Bug report for focmm).

Any feedback, statements and …

cd /var/log
ll -d -Z mysql* mysql/*
mkdir mysql
chown mysql: mysql
semanage fcontext -a -t mysqld_db_t "/var/log/mysql/(/.*)?"
restorecon -Rv /var/log/mysql
ll -d -Z mysql* mysql/*

And Non-standard database set up with SELinux

/usr/sbin/logrotate /etc/logrotate.conf

On StackExchange for Database Administrators I recently have seen a question which attracted my interest.

The question puzzled me a bit because the answer seems too easy. Further the question was not so clear. An all theses factors smell dangerous…

About time - was, is and will be

How can I find out if the database “was” shutdown slowly? This is quite easy: Look into your MySQL Error Log and there you will find a log sequence similar to the following:

2020-03-30T08:03:36.928017Z 0 [System] [MY-010910] [Server] /home/mysql/product/mysql-8.0.19-linux-glibc2.12-x86_64/bin/mysqld: Shutdown complete (mysqld 8.0.19)  MySQL Community Server - GPL.

Ups! There are no more “shutting down …” messages like in MySQL 5.7:

2020-03-30T08:04:49.898254Z 0 [Note] Giving 1 client threads a chance to die gracefully
2020-03-30T08:04:49.898266Z 0 [Note] Shutting down slave threads
2020-03-30T08:04:51.898389Z 0 [Note] Forcefully disconnecting 1 remaining clients
2020-03-30T08:04:51.898433Z 0 …

The InnoDB deadlock detector was rewritten in MySQL 5.7.1, in a merge commit that does not mention any WL or bug number, nor any reviewer. I did not review those changes, and I cannot say whether the algorithmic complexity of the deadlock checker was reduced. Possibly the rewrite replaced procedural recursion with iteration over a data structure that explicitly represents a stack.

I think that the InnoDB locking performance could be significantly improved by extending the use of implicit locking to UPDATE and DELETE operations, as noted in MDEV-16232. It could also be helpful to merge multiple record log bitmaps into a single bitmap per page, with 4 bits per record, as noted in MDEV-16406.

Marko Mäkelä, Lead Developer InnoDB
MariaDB Corporation

• fpmmm 2.2.1 Release Notes, Release Date: 13 February 2026
• fpmmm 2.2.0 Release Notes, Release Date: 4 September 2025 → see v2.2.1
• fpmmm 2.1.0 Release Notes, Release Date: 5 December 2023
• fpmmm 2.0.0 Release Notes, Release Date: 18 May 2022
• fpmmm 1.2.0 Release Notes, Release Date: 11 June 2020
• fpmmm 1.1.0 Release Notes, Release Date: 17 December 2019
• fpmmm 1.0.2 Release Notes, Release Date: 7 March 2019
• fpmmm 1.0.1 Release Notes, Release Date: 9 February 2017
• fpmmm 1.0.0 Release Notes, Release Date: 2 October 2016
• fpmmm 0.10.9 Release Notes, Release Date: 17 August 2016
• fpmmm 0.10.6 Release Notes, Release Date: 2 August 2016
• fpmmm 0.10.5 Release Notes, Release Date: 31 July 2015
• fpmmm 0.10.4 Release Notes, Release Date: 16 May 2015
• fpmmm 0.10.3 Release Notes, Release Date: 1 May 2015
• fpmmm 0.10.2 Release Notes, Release Date: 30 April 2015
• fpmmm 0.10.1 Release Notes, Release Date: 19 April 2015
• fpmmm 0.10.0 Release Notes, Release Date: 16 April 2015
• fpmmm 0.9.3 Release Notes, Release Date: 24 May 2014
• fpmmm …