Support reindex

[ThomasArdal]

Other clients for ElasticSearch supports reindexing entire index as described here: http://www.elasticsearch.org/blog/changing-mapping-with-zero-downtime/#_reindexing_your_data

It would be cool to support this flow in NEST as well.

[Mpdreamz]

Yes it would @ThomasArdal :)

I took a first jab at it see:

https://github.com/Mpdreamz/NEST/blob/dabb70f1232954037fe012f0f3cc86bbb282a190/src/Nest.Tests.Integration/Index/ReindexTests.cs

[ThomasArdal]

Looking sweet. I would be nice to be able to reindex with minimum number of parameters. Just reindex the current index to a new index ending up with the same name and the metadata from the mappings.

[Mpdreamz]

Ahh just specifying FromIndex() and ToIndex() will do that, all the others are optional.

Also CreateIndex() is initialized from with the settings from the FromIndex() so you only need to specify to modifications you'd want instead of reapplying all the settings.

[ThomasArdal]

Very nice. Great work!

[Mpdreamz]

Ok i lied, in the 0.11.3.0 release Query() and CreateIndex() are mandatory. Just fixed this in the commit after the release with a unit to test that they are in fact optional. Will make it into the next release :)

[ThomasArdal]

Cool!

[eamocanu]

I have a parent child index and calling reindex with object type throws a no documents exist in index exception: client.Reindex(...) -> exception
I have to reindex each type one after another; the problem becomes that if index already exist cannot use reindex() to insert other documents into it -> exception is thrown again.

Has anyone else found this behaviour?

[benbenwilde]

In my opinion, the NEST implementation of Reindex is too opinionated.

1. You must create a new index during the reindex (can't just set it up yourself and then call re-index)
2. You must setup all the settings and mappings during the reindex (you can't use your method of choice for these things, and the fluent interface is not as easy as alternative methods)
3. The from-index must have documents

The current implementation may work for some, but for those who are looking for another way:
http://stackoverflow.com/a/34867857/2284031