zero downtime importing

[pseidemann]

hello,
currently when I do Model.import (elasticsearch-model), the whole index will be wiped out and then rewritten. this method is not an option when the system is live. I would need to shutdown all clients somehow before doing the import.
because of this I would propose to implement a zero downtime method like searchkick did (see https://github.com/ankane/searchkick/blob/master/lib/searchkick/index.rb#L151). their method Model.reindex calls the method reindex_scope which creates a new index with the current timestamp as a suffix, fills this index, and then changes the index alias to this newly created index.
what do you think?

[karmi]

There's probably an issue opened for that already... I'm not sure how much "magic" to provide, because:

(...) the whole index will be wiped out and then rewritten (...)

Not really -- the method is much more flexible and allows to (re)index into a completely different index. Then it's mostly a matter of setting up aliases and so on so everything adds up.

[pseidemann]

I think #234 is related.
I can't find anything about managing aliases in the elasticsearch-rails documentation.
from my perspective, implementing this "magic" has great value. it is even recommended by the elastic blog itself https://www.elastic.co/blog/changing-mapping-with-zero-downtime