In our application, we are using the elastic search of 2.3.4 and kibana 4.5.3 version. It has already indexed data. Recently, we decided to upgrade elastic search to 5.5.2 version and kibana to 5.5.2 version.
Some time back, we had upgraded elastic search from 1.x to 2.3.4. At that time, we had re-indexed the data as part of migration.
From the elastic search and kibana upgrade document, we are not clear on re-indexing the current data in upgrading ES from 2.x to 5.x.
Do we need to perform re-index elastic search data as part of migration ?
Thanks in advance
Data written with Elasticsearch 2.x (Lucene 5) can be read by Elasticsearch 5.x (Lucene 6) without a reindex. Generally, Lucene can always write in its current version format and read the previous one; but it cannot read the one before. So if you had data written with Elasticsearch 1.x you would need to reindex, going from 2.x to 5.x won't need it.
And if you are not already doing it, use the migration plugin to see what needs to be changed before the upgrade.