How to reindex ElasticSearch quickly?
问题 I have an ElasticSearch index with around 200M documents, total index size of 90Gb. I changed mapping, so I would like ElasticSearch to re-index all the documents. I wrote a script that creates a new index (with the new mapping), then goes over all the documents in the old index and puts then into the new one. It seems to work, but the problem is that it works extremely slowly. It started with 300 documents / minute two days ago, and now the speed is 150 documents/minute. The script runs on a