Migrate solr standalone index to solrcloud

Question

There are indexes of some solr cores which I convert them from solr4 to solr6 but in solr standalone mode. so they don't have the "version" field that solrcolud require.

Here now I want to migrate to solrcloud 6 and I need to put them under cluster. Because the version field dose not exist there in these indexes when I put them Under a solrcloud leader core on the data directory the replicas in the shard didn't update as I saw. so I decided to read them by lucene, get each doc fields, add them to a solrdoc and then put them doc by doc in solrcloud. But cause there are fields that not stored in these indexes so all fields that exist here in these indexes don't move there.

At the end it seems there is no way for me than re-indexing. I appreciate if there is any better idea or solutions that can help me migrate more easily.

Answer 1

If there is any chance to reindex, just do so, it's going to be the best in the end (you have to deal with two separate issues: a) migrate from 4.X to 6.0 and b)from standalone to SolrCloud...it's going to be messy).

If you cannot reindex:

1. are all your fields stored OR have docValues=true? If so, you can get the original contents of your docs. Read them and index them with solrj or with some script.
2. if not, and you have a version field: try to manually put the index in Solrcloud. Not straighforward, but possible.
3. if you don't have a version field, I think it is impossible to put the index as is in Solrcloud (although some post on the net make you think it is). You could try to write some lucene code to add version field to all docs (with values that make sense), but this should be the very last resort.