Basic Concepts Flashcards
1
Q
What is the role master node?
A
- Coordinates the clusters
- Keep track of the data
- Make sure data is balanced
- Coordinate traffic
2
Q
What is the role of a data node?
A
- Store the data
- Perform the index and search operations
3
Q
What is an index in elastic search?
A
- It’s the abstraction where you documents are stored and indexed.
- It’s broken into primary shards and replica shards.
4
Q
What is a primary shard?
A
The primary location where documents are stored and retrieved.
5
Q
What is a replica shard?
A
- A copy of a shard that is maintained into a different node and can be promoted to “primary” in case the current primary goes offline.
6
Q
What is a shard?
A
Shards are blocks of data that are distributted cross nodes to balance the data.
7
Q
Draw a diagram the elastic architecture with the basic concepts.
A
8
Q
What is the basic unit of storage in elastic?
A
A document.
9
Q
What is a document comprised of in elastic?
A
It’s a json object with arbritrary number of fields.
10
Q
Describe the 3 states an index can be in
A
- Green: All primary shards and their replicas are online (All data is available with replication).
- Yellow: The index is missing replicas. (All data is available, but we don’t have a “backup”)
- Red: A primary shard is missing. (Data is missing)
