I was upgrading from ES 2.x to 5.x, and then using the X-Pack Upgrade Assistant/Reindex helper to upgrade the indices as required. Unfortunately I hit a Java heap space problem and the elasticsearch process crashed after it had been running for more than 2 days.
I now have my original indices still intact, AND a partial reindexed version of one of them -- it was about 85% completed. Is there any way to get it to continue where it left off ? Or is my only option to delete the "reindexed" incomplete index and start it all over again ? I tried to start the reindex helper again and of course it complains that the index it wants to create already exists, but I can see from the size that it is not a complete index.