# Best reindex strategy to change only the number of Shards **URL:** \ **Category:** Elasticsearch\ **Created:** [July 12, 2014, 1:19pm UTC](https://discuss.elastic.co/t/best-reindex-strategy-to-change-only-the-number-of-shards/18621 "2014-07-12T13:19:52Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Chris\_Berry\_2](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/chris_berry_2/32/1366_2.png) [@Chris\_Berry\_2](https://discuss.elastic.co/u/Chris_Berry_2)\ **Post date:** [July 12, 2014, 1:19pm UTC](https://discuss.elastic.co/t/best-reindex-strategy-to-change-only-the-number-of-shards/18621/1 "2014-07-12T13:19:52Z")
Hello, I have a very large Index in ES (millions of entries over 100s of GB) with too few Shards. And I want only to create the same Index but with more, smaller, efficient Shards. And I would love it if this could happen quickly (minutes?) My googling indicates that the elasticsearch-reindex Plugin ([https://github.com/karussell/elasticsearch-reindex](https://github.com/karussell/elasticsearch-reindex)) is the best approach. Is that still the case?? Under the covers elasticsearch-reindex uses the recommended scan-and-scroll technique. But reading the doc/code in the elasticsearch-reindex Plugin, they indicate that perhaps they should have implemented it as a River. And I’ve not been able to find a River that accomplished this same task. It seems that this might be a pretty common thing to need to do, and that there may be a very efficient way to accomplish it that I am missing. And it seems that it might be fastest to have some sort of very fast streaming process that could essentially stream the entries of indexOld to indexNew with a new number of Shards. Is elasticsearch-reindex still the best tool for this job?? (I am on ES 1.0.2) Thanks much, — Chris -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/14711f9d-0848-4923-b00a-62cd85d8a337%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/14711f9d-0848-4923-b00a-62cd85d8a337%40googlegroups.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![spinscale](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/spinscale/32/25011_2.png) [@spinscale](https://discuss.elastic.co/u/spinscale)\ **Post date:** [July 18, 2014, 9:57am UTC](https://discuss.elastic.co/t/best-reindex-strategy-to-change-only-the-number-of-shards/18621/2 "2014-07-18T09:57:54Z")
Hey, maybe there is no need to reindex? Cant you just index all your new data into another index and use an alias to search on both indices? You might want to watch [https://www.youtube.com/watch?v=gBOhCNcjC7k](https://www.youtube.com/watch?v=gBOhCNcjC7k) --Alex On Sat, Jul 12, 2014 at 3:19 PM, Chris Berry [chriswberry@gmail.com](mailto:chriswberry@gmail.com) wrote: > Hello, > > I have a very large Index in ES (millions of entries over 100s of GB) with > too few Shards. > And I want only to create the same Index but with more, smaller, efficient > Shards. > And I would love it if this could happen quickly (minutes?) > > My googling indicates that the elasticsearch-reindex Plugin ( > [GitHub - karussell/elasticsearch-reindex: Simple re-indexing. To backup, apply index settings changes and more ElasticMagic](https://github.com/karussell/elasticsearch-reindex)) is the best approach. > Is that still the case?? > Under the covers elasticsearch-reindex uses the recommended > scan-and-scroll technique. > > But reading the doc/code in the elasticsearch-reindex Plugin, they > indicate that perhaps they should have implemented it as a River. > And I’ve not been able to find a River that accomplished this same task. > > It seems that this might be a pretty common thing to need to do, and that > there may be a very efficient way to accomplish it that I am missing. > And it seems that it might be fastest to have some sort of very fast > streaming process that could essentially stream the entries of indexOld to > indexNew with a new number of Shards. > > Is elasticsearch-reindex still the best tool for this job?? > (I am on ES 1.0.2) > > Thanks much, > — Chris > > -- > You received this message because you are subscribed to the Google Groups > "elasticsearch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). > To view this discussion on the web visit > [https://groups.google.com/d/msgid/elasticsearch/14711f9d-0848-4923-b00a-62cd85d8a337%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/14711f9d-0848-4923-b00a-62cd85d8a337%40googlegroups.com) > [https://groups.google.com/d/msgid/elasticsearch/14711f9d-0848-4923-b00a-62cd85d8a337%40googlegroups.com?utm\_medium=email&utm\_source=footer](https://groups.google.com/d/msgid/elasticsearch/14711f9d-0848-4923-b00a-62cd85d8a337%40googlegroups.com?utm_medium=email&utm_source=footer) > . > For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/CAGCwEM8%3DuhT2zJkjpWjKOxMqC6nTPs8riJAdjUf-0sngKbVoMQ%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAGCwEM8%3DuhT2zJkjpWjKOxMqC6nTPs8riJAdjUf-0sngKbVoMQ%40mail.gmail.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 6, 2017, 1:14am UTC](https://discuss.elastic.co/t/best-reindex-strategy-to-change-only-the-number-of-shards/18621/3 "2017-07-06T01:14:57Z")