Index Data Ingestion

Elastic Stack Elasticsearch
1

Hi,
I am trying to understand how the ingestion works.
Lets say I created an index with 6 primary shards, 1 replica.
and I am ingesting to the cluster (say logstash is continuously pushing data) to a coordinating only node.

Can somebody help me understand how the data flows from when the co-ordinating node receives the data.
How the co-ordinator node forwards the incoming data to different shards,
does it fill one after another or how?

2

Each document in the bulk request gets assigned a document ID if one is not provided. The ID is hashed in order to determine which shard the document should go to. The bulk request is then split up and forwarded in parallel to the appropriate primary shards.