Elasticsearch: useful commands for DBAs

As a production DBA, you can fall into a situation where you have to act on an environment you do not know.

It can be very difficult to understand how the architecture was designed, but if you know the right commands, you can get a quick overview and all the information you need to start working.

Today, I’m going to give you these basic commands that will help you understand how an Elasticsearch installation was performed on an RHEL system.

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MongoDB sharded cluster topology

Today, I’m going to share with you a bash script that gives you a quick overview of the topology of your MongoDB cluster.

It will give you:

  • The list and status of your mongos
  • The list and status of your config server
  • The list and status of every replica set members present in your cluster (including secondary members and arbiters), plus:
    • The date of the last role change between primary and secondary
    • The apply lag between primary and all secondary members
    • The oplog window
  • The balancer status

You can download the script on my GitHut repository “MyDBAWorld”.

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Get chunk distribution for all databases in a MongoDB cluster

One of the most important tasks for maintaining good performance in a sharded MongoDB cluster is to ensure optimal chunk distribution across each cluster member.

I’m not going to talk about picking a good shard key for your collections because the MongoDB documentation on the subject is pretty good. But I will share with you a script that I use to get the chunk distribution for all databases on a MongoDB sharded cluster.

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