How to identify if MongoDB Backup Snapshot Encryption is enabled

Question: How can I identify if Backup Snapshot Encryption for MongoDB using the KMIP compliant management is enabled & configured? Answer: To have MongoDB Backup Snapshot Encryption enabled the DBA would apply a master key that a KMIP-compliant key management appliance would generate and maintain. This master key encrypts key that encrypts the database. As outlined in the MongoDB documentation : "Prerequisites : A host running KMIP-compliant key management to generate and store encryption keys. IMPORTANT Clusters running MongoDB FCV 4.2 or later must use KMIP servers. These clusters don’t support local key management using files. IMPORTANT You must maintain... Read more →

The Amazing Babelfish for PostgreSQL by AWS

Some interesting news in the AWS re:Invent 2020 - Keynote with Andy Jassy . Introduction of the new Babelfish for PostgreSQL , aiming to to offer a new translation capability to run SQL Server apps on Aurora PostgreSQL. One of the main selling points is the capacity to understand SQL Server proprietary dialect t-sql and the Tabular Data Stream (TDS) Protocol Some underlying logic , which has led to the development & introduction of Babelfish for PostgreSQL: 1) Databases are hard to manage which partly has led to the massive uptake on managed RDBMS service. Despite growth in AWS managed... Read more →

How to execute a js file in MongoDB

Question: I have a js file - which iterates through some MongoDB collections - and currently I execute on an adhoc basis using the mongo shell. I now need to schedule this process on a regular basis and researching some effective methods to use? Can you supply some examples \ methods to deploy Answer: I use two main methods to execute external js files . The first method utilises mongo shell & the second method use the MongoDB load function. Using this method gives you flexibility to trigger steps with a scheduler such as Crontab Method 1 : Using the... Read more →

How to use MongoDB column alias in SQL Server SELECT

Question: I am accessing data through a SQL Server Linked Server . The Linked Server is interfacing a MongoDB ODBC - connected to a MongoDB. The MongoDB ODBC connects to the BI Connector - which in turn extracts some collections. When the results are returned using the SQL Server OPENQUERY functionality , the dot nation is used to represent some columns. I want the columns presented without dot notation. How can I return an alias? Answer: When using OPENQUERY command through SQL Server connecting to MongoDB - it will present with dot notation. For Example: select * from OPENQUERY(MongoDB_TEST,'select *... Read more →

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 →