Category Archives: Databases

A NoSQL database provides a mechanism for storage and retrieval of data that is modeled in means other than the tabular relations used in relational databases.
A relational database management system is a database management system based on the relational model of data.

AWS: Redshift – quick start and SQL-workbench connection config

18 October 2019
 

 Our data-analytics team eventually started to play with an AWS Redshift cluster instead of the MariaDB RDS service. Actually, the current task is to spin up a simple Proof of Concept Redshift’s cluster in the AWS. Let’s do it quickly, without details – if this will go to the Production, I’ll add another post with… Read More »

PostgreSQL: FATAL: Peer authentication failed for user “name”

11 September 2019
 

 A quick note mainly for myself on how to enable remote access in PostgreSQL and create its database dump. An EC2-server moved to our AWS account with one website. During an attempt to connect to the PostgreSQL running on this host – the “FATAL: Peer authentication failed for user “name”” appears. And the same error… Read More »

Redis: main configuration parameters and performance tuning overview

10 September 2019
 

 Currently configuring Redis server as our backend caching service and during that wrote this post with some things to pay attention at in Redis config file. Shortly enough but with links to other posts or documentation. Let’s begin with the redis-benchmark utility. Will be installed alongside with Redis service, so can be used right after… Read More »

SonarQube: solving “Unrecoverable indexation failures” and Elasticsearch “Disk watermark exceeded” errors

29 August 2019
 

 We are using SonarQube started from a Jenkins jobs. See more at SonarQube: running tests from Jenkins Pipeline in Docker. So, the SonarQube is started from the Jenkins – all good here, but inside SonarQube we can see errors: java.lang.IllegalStateException: Unrecoverable indexation failures: 1 errors among 1 requests at org.sonar.server.es.IndexingListener$1.onFinish(IndexingListener.java:39) at org.sonar.server.es.BulkIndexer.stop(BulkIndexer.java:122) … And host… Read More »

Redis: fork – Cannot allocate memory, Linux, virtual memory and vm.overcommit_memory

28 August 2019
 

 Currently, I’m configuring a Redis as a caching service for our application and during that, I faced with the question: do I need to set vm.overcommit_memory to the value 1, i.e. disable it – or not? The question is quite old for me, see The story, but only now I found time to get to… Read More »

AWS RDS: “SQLSTATE[22001] – Data too long for column” using MariaDB 10.2

8 August 2019
 

 We have a PHP-application with the AWS RDS MariaDB as a backend. On the previously used 10.0 version all was good, but right after we upgraded to the MariaDB 10.2 – got errors during tests: PDOException: SQLSTATE[22001]: String data, right truncated: 1406 Data too long for column ‘name’ at row 1 in /data/projects/projectname/vendor/yiisoft/yii2/db/Command.php:1290 The first… Read More »

AWS: MariaDB RDS – kill: You are not owner of thread

14 May 2019
 

 We have AWS RDS with MariaDB. The error below and its solution aren’t specific to AWS RDS and MariaDB. The next error appears during attempt to kill() a thread in MySQL: The solution is to use the mysql.rds_kill() procedure instead: Execute it: For Azure MySQL, there is a similar procedure mysql.az_kill(). Done.

TestRail: reset admin password

13 May 2019
 

 We have a TestRail installation but suddenly lose its Admin user password. The Reset Password says that “Email sending failed” although email was configured and users are able to get emails from the server. Also, the log /var/www/testrail.example.com/logs/log-2019-05-13.php didn’t says anything so will reset password in another way – by update this TestRail MySQL database… Read More »

Redis: replication, part 4 – writing an Ansible role fore the Master-Slave replication with Redis Sentinel provisioning

15 April 2019
 

 The next post from the Redis replication series. Previous parts: Redis: replication, part 1 – an overview. Replication vs Sharding. Sentinel vs Cluster. Redis topology. Redis: replication, part 2 – Master-Slave replication, and Redis Sentinel Redis: replication, part 3 – redis-py and work with Redis Sentinel from Python The task now is to write an… Read More »