How to restore a single MongoDB database from a Snapshot Backup

Get the MongoDB snapshot archival download link You will need to obtain this link from the MongoDB Operations Manager. (There is an alternative option to scp the .tar.gz file ).From the Continuous Backup section section obtain the download link Log onto the server and download the file using using curl. ----curl is a useful tool to download the tar file curl download_url --output myfile.tar.gz ----unpack the tar file tar -xvf myfile.tar.gz ----the temp-database-path should be accessible by mongod ----e.g of creating the the temp-database-path mkdir temp-database-path chown mongod:mongod temp-database-path mv Start a new, temporary MongoDB process on a... Read more →

How to stop and start MariaDB on Linux

Question: How can I stop ,start and check status for MariaDB on Linux? Answer: The commands will depend on whether you're using an older system with system V init or with systemd . I'll present both and decide depending on your server setup --using system V init (assuming you're calling "mariadb") service mariadb status service mariadb start service mariadb stop service mariadb restart --using systemd systemctl status mariadb systemctl start mariadb systemctl stop mariadb For more MariaDB commands use MariaDB Cheatsheet Read more →

How to use mongodrdrl to extract a MongoDB collection schema

mongodrdl : what is it ? It is a tool packaged with MongoDB BI Connector. It has a number of functions to assist is mapping and manipulating schemas. How can I use mongodrdl? This is an example of a mongodrdl command line request. In this example the mongodrdl command line tool samples the namespaces of the database and collection specified. For more options check the official MongoDB BI Connector documentation mongodrdl sample --host "myserver" --port 27017 --authenticationDatabase admin --username myAdmin --password myPw1 --db db1 --collection mycollection --out myCollection.drdl This is a snippet from the file output schema: - db: myDB... Read more →

How to fix Crontab -e - You are not allowed to use this program (crontab)

Question: I've received a new server and logon, trying to use Crontab but getting this error message: You (your_logon) are not allowed to use this program (crontab) See crontab(1) for more information How can I fix? Answer: It looks like you are experiencing a situation where only root can use crontab - but other logon accounts require some extra steps. On Linux there are two files which control the access to crontab: /etc/cron.allow /etc/cron.deny You will need to add the logon account to the /etc/cron.allow file. The way to add the logon account is to --su to root and then... Read more →

How to easily install Podman on Red Hat Linux

Databases on containers is going mainstream. A great way to get comfortable with Containers and exploring the difference between a more traditional DBMS to OS relationship is to install Podman on Linux , download some images and start learning. Podman is a daemonless, open source, Linux native for sharing and deploying applications using Open Containers Initiative (OCI) Containers and Container Images Some terminology: An image is a binary containing the requirements for running a single container. Metadata is included to describe various needs The basic unit of Podman apps are termed as containers. Containers isolate the running processes , and... Read more →

How to change PostgreSQL database data directory

Question: The Postgres data_directory is showing a value via the SHOW data_directory command. postgres=# SHOW data_directory; data_directory ------------------------ /var/lib/postgres/data (1 row) How can I change the database directory to another directory? Answer: The steps below are a standard approach. The steps will vary according to specific requirements, and may require a more customised approach Step 1 - Identify current data directory path SHOW data_directory; Step 2- Stop Postgresql services systemctl status systemctl stop Step 3 - create a blank directory on the target path e.g mkdir /mydirectory/data --change ownership to the postgres user , for example chown postgres:postgres... Read more →

How to fix Table doesn't exist in engine error for MariaDB Error 1932

Question: When attempting a mysqldump on one of the databases on a MariaDB server with this command I received the error message mysqldump: Got error: 1932: "Table 'schema1.myTable' doesn't exist in engine" when using LOCK TABLES mysqldump -u myun -p database_name > /mariadb/backups/mydb1171117.sql Description: Backup of [~myDB1~] MySQL database failed. The error message [~mysqldump: Couldn't execute 'show create table `my_code`': Table 'mydb1.my_code' doesn't exist in engine (1932) ~] is received during backup. Source: myserver1, Process: MySqlBackupChil How can I fix? In summary - some files were moved around and this has caused the issue Answer:I've found this error message appears... Read more →

How to use auto-increment with PostgreSQL sequence

A developer contacted me to to tell me they were experiencing problems with enabling an auto-increment on a PostgreSQL table.He wanted to know if the privileges assigned to his user credentials had the right level of permission to create a sequence. I reviewed the privileges and identified some missing details: GRANT ALL PRIVILEGES ON ALL SEQUENCES IN SCHEMA myschema1 TO user1; As a test I logged on as the user's credentials and completed some simple validation tasks to confirm they could complete a CREATE SEQUENCE and add to a table. Step 1 : Create a simple SEQUENCE CREATE SEQUENCE myschema1.jvtest_seq;... Read more →

Announcing Powerful Rules for Disruptors with MongoDB

An interesting presentation highlighting the power of keeping the pressure on but making as many friends as possible - to create change . Modernizing and rethinking legacy platforms can be a daunting task. This presentation describes cultural buttons to push - and how to start small , but keep growing. Starting small - allows developing expertise at a granular level which is the foundation of hyperscale These are some highlights from the presentation- with a link to the presentation Rules for Disruptors - Making, Managing and Scaling the Case for Change with MongoDB by Jeff Needham - Architect The most... Read more →

How to fix - Cannot connect to the Docker daemon

Question: I'm getting this error message when attempting to connect to the Docker daemon ? Can you supply a method to fix this issue docker info Cannot connect to the Docker daemon at tcp://localhost:2375/usr/lib/systemd/system/docker.socket. Is the docker daemon running? Answer: I've experienced this problem previously - and this is the way I worked around the problem.Let me know if this doesn't fix the issue Add your self to the docker group usermod -aG docker $USER Fix permissions on docker socker and command. sudo chgrp docker /usr/bin/docker sudo chgrp docker /var/run/docker.sock $ ll $(which docker) -rwxr-xr-x 1 root docker 18991768 08.07.2017... Read more →