Reindexing Elastic search via Bulk API, scan and scroll

Question

I am trying to re-index my Elastic search setup, currently looking at the Elastic search documentation and an example using the Python API

I'm a little bit confused as to how this all works though. I was able to obtain the scroll ID from the Python API:

es = Elasticsearch("myhost")

index = "myindex"
query = {"query":{"match_all":{}}}
response = es.search(index= index, doc_type= "my-doc-type", body= query, search_type= "scan", scroll= "10m")

scroll_id = response["_scroll_id"]

Now my question is, what use is this to me? What does knowing the scrolling id even give me? The documentation says to use the "Bulk API" but I have no idea how the scoll_id factors into this, it was a little confusing.

Could anyone give a brief example showing my how to re-index from this point, considering that I've got the scroll_id correctly?

Answer 1

here is an example of reindexing to another elasticsearch node using elasticsearch-py:

from elasticsearch import helpers
es_src = Elasticsearch(["host"])
es_des = Elasticsearch(["host"])

helpers.reindex(es_src, 'src_index_name', 'des_index_name', target_client=es_des)

you can also reindex the result of a query to a different index here is how to do it:

from elasticsearch import helpers
es_src = Elasticsearch(["host"])
es_des = Elasticsearch(["host"])

body = {"query": {"term": {"year": "2004"}}}
helpers.reindex(es_src, 'src_index_name', 'des_index_name', target_client=es_des, query=body)