Basic Concepts Flashcards

1
Q

What are the functions of the master node role?

A
  • Coordinates the clusters
  • Keep track of the data
  • Make sure data is balanced
  • Coordinate traffic
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2
Q

What is the role of a data node?

A
  • Store the data
  • Perform the index and search operations
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3
Q

What is an index in elastic search?

A

It’s the abstraction where you documents are stored and indexed.

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4
Q

What is a primary shard?

A

The primary location where documents are stored and retrieved.

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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.
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6
Q

What is a shard?

A

Shards are blocks of data that are distributted cross nodes to balance the data.

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7
Q

Draw a diagram the elastic architecture with the basic concepts.

A
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8
Q

What is the basic unit of storage in elastic?

A

A document.

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9
Q

What is a document comprised of in elastic?

A

It’s a json object with arbritrary number of fields.

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10
Q

What are the 3 states an index can be in?

A
  • Green
  • Yellow
  • Red
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11
Q

How are Indexes organized?

A

They are split into:
* Primary shards
* Replica shards

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12
Q

What does a GREEN index mean?

A

All primary shards and their replicas are online (All data is available with replication).

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13
Q

What does a YELLOW index mean?

A

The index is missing replicas. (All data is available, but we don’t have a “backup”)

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14
Q

What does a RED index mean?

A

A primary shard is missing. (Data is missing)

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