Are there any tools that read all documents in an index, and write them to a new index?
This is useful if you have an index with say 50 shards, and you have 50 machines, but you want to expand this to 100 machines. This way you would just create a new index, read all documents from the old index, then write the new index, then swap the index names.
There are some problems with some naive approaches:
how do you make it work in parallel so it works on all nodes at once?
how do you make it resume so that if it crashes it can pick up where it left off.
I mean I think I can dive in and write this, but would be nice if something worked out of the box.