Sorting on length of field in the result

Elastic Stack Elasticsearch
1

We use elasticsearch with couchdb, with the couchdb-river installed.

Now everything works fine, but now I want to be able to sort the results
we get from elasticsearch.

The first problem is that the date field is not a valid date, because
the format is something like this from the database:
2012-12-27T18:58:22Z

And there was a mapping to make it treat like a string. But now I would
need to sort on it, so I should probably change the mapping.

But I have another question about that, should I create a new index
with that mapping or use the PUT Mapping API? What's the difference
between the two possibilities?

The second problem is that I want to sort on things that require some
computation.

For example in the index I have the field:
{'ideas': ['first', 'second', 'third']}

And I need to be able to sort on the length of that list.

How can I do it?
I don't find a scripting way to do it, or a possible core type.

Is the only way to keep track of the number of ideas (and add the field)
in couchdb maybe?

Thanks, Andrea

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2

There is no difference between creating an index with a mapping and putting
mapping after you create an index.

You can use script to sort based on the number of ideas using Script Based
Sorting http://www.elasticsearch.org/guide/reference/api/search/sort.html.
However, keeping the count in your application and indexing it as a
separate field might be a much better idea from the performance
perspective.

On Friday, January 11, 2013 5:23:25 AM UTC-5, andrea crotti wrote:

We use elasticsearch with couchdb, with the couchdb-river installed.

Now everything works fine, but now I want to be able to sort the results
we get from elasticsearch.

The first problem is that the date field is not a valid date, because
the format is something like this from the database:
2012-12-27T18:58:22Z

And there was a mapping to make it treat like a string. But now I would
need to sort on it, so I should probably change the mapping.

But I have another question about that, should I create a new index
with that mapping or use the PUT Mapping API? What's the difference
between the two possibilities?

The second problem is that I want to sort on things that require some
computation.

For example in the index I have the field:
{'ideas': ['first', 'second', 'third']}

And I need to be able to sort on the length of that list.

How can I do it?
I don't find a scripting way to do it, or a possible core type.

Is the only way to keep track of the number of ideas (and add the field)
in couchdb maybe?

Thanks, Andrea

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