Upgrade from 1.7.2 to 5.4.0

Elastic Stack Elasticsearch
1

Hi there,
I have lots of indices that created and pump lots of data in v1.7.2. We are going to upgrade to 5.4.0 recently, I wonder do we have any solution that smoothly migrate data to new version?

My concern is:
Indexed documents were not enabled _source, can we still use solution guide here
https://www.elastic.co/guide/en/elasticsearch/reference/current/reindex-upgrade.html

Upgrading with reindexing from remote?

2

Without _source, you cannot use the Reindex API. And without the reindex API, you cannot hope to do a one-shot, in-place migration from 1.7 to 5.4, as the Lucene data structures of the 1.7 indices are not compatible.

You may be able to go to 2.x, add and remove a document, do a forceMerge, and force the segments to a newer format, then do an in-place upgrade to 5.x. I say may because I'm still not 100% this can be done.

Not having _source has kind of hamstrung your upgrade path.

3

Thanks, I'll try your solution. Hope that help.
The worst case is...I have to drop those indices.