For Storing Data for with Few Transactions and Little Loading with a Need for Compression, Would a Column-Oriented Database Be Better than a Row-Oriented Database?

Problem scenario
You are trying to select a database that is right for your needs. You will not be doing many transactions. The database does not need to support regular ETL or OLTP. You are going to have a large database, and you want it to compress to the smallest size possible. In some cases a column-oriented database better than a row-oriented database. What type of database should you use for this situation?

How Do You Install MongoDB on RHEL 8.x?

Problem scenario
You want to install MongoDB on a RHEL server. What do you do?

1. Create this file: /etc/yum.repos.d/mongodb-org-4.4.repo

name=MongoDB Repository

  1. Run these commands:

sudo yum -y update
sudo yum -y install mongodb-org

  1. Test the installation by running this: mongod -version

If you are using Debian or Ubuntu,

What Database Does Elastic Search Use?

What SQL database underlies Elastic Search?

There is no relational database for Elastic Search.

Elastic Search will have a cluster that is composed of nodes. Nodes are composed of indexes. Indexes are supported by shards. Shards have primary and replica copies. The replica copies vary. The shards are essentially Lucene indexes (according to this site).

How Do You Install and Configure the rdf4j Server and Workbench GUI?

Problem scenario
You want to use the rdf4j (Resource Description Framework for Java). You want to install the rdf4j server and workbench. You are using Debian 9 Linux. What should you do?

i. We recommend having a 30 GB of hard disk free.

ii. We recommend having 5.75 GB of RAM (it can be a combination of RAM and swap space).

How Do You Troubleshoot Cassandra when It Hangs on the Message “ Initializing”?

Problem scenario
You start Cassandra with this command: ./bin/cassandra
You see one of the following messages:

INFO [MigrationStage:1] 2018-04-06 19:01:07,144 – Initializing system_auth.resource_role_permissons_index
INFO [MigrationStage:1] 2018-04-06 19:01:07,163 – Initializing system_auth.role_members

No progress is happening. What should you do?

Possible Solution #1. Try rebooting the server. This could help the problem.

What Do You Do when Cassandra Stalls on “Initializing IndexInfo”?

Problem scenario
When you start Cassandra you see a message such as this:

INFO [main] 2018-02-03 08:45:55,257 – Initializing system.IndexInfo

What should you do?

Possible Solution #1
Try rebooting the server. This could help the problem.

Possible Solution #2
This next one is merely a workaround. It is not a best practice.

Why Would a MongoDB Container Work on an Ubuntu Host but Not a SUSE Host?

Problem scenario
You have two Linux servers in AWS, and each one has the same flavor (i.e., same amount of RAM and same number of processors). One is Ubuntu and another is SUSE. These commands will create working containers in Ubuntu:

docker run –name name1-mongo -d mongo
docker run –name name2-mongo -d mongo:2

This command will not create a working container in SUSE:

docker run –name name2-mongo -d mongo:2

The container that is created will never start.