Elasticsearch indices to be created with number_of_replicas as default as 0.

[AmirSabjan]

Description:

Currently, Elasticsearch indices created through Haystack use the default cluster setting of 1 replica shard. For Haystack deployments, it's desirable to have the option to create indices with 0 replicas to optimize resource utilisation.

Proposed Change:

Modify Haystack's self._client.indices.create(index=index, body=settings) call to accept a parameter specifying the desired number of replicas. This parameter should then be incorporated into the settings body passed to the Elasticsearch API.

Example Code:

Python

class ElasticsearchDocumentStore:
    def __init__(self, *, hosts: Optional[Hosts] = None, index: str = "default", number_of_replicas=0, **kwargs):
 
      """
        Creates an Elasticsearch index with the specified number of replicas.
      
        Args:
            index (str): The name of the index to create.
            number_of_replicas (int, optional): The desired number of replicas for the index. Defaults to 0.
        """
        settings = {
            "number_of_replicas": number_of_replicas
        }
        if not self._client.indices.exists(index=index):
          self._client.indices.create(index=index, body=settings)