elasticsearch/docs/reference/migration/migrate_2_1.asciidoc

[[breaking-changes-2.1]]
== Breaking changes in 2.1

This section discusses the changes that you need to be aware of when migrating
your application to Elasticsearch 2.1.

=== Search changes

==== `search_type=scan` deprecated

The `scan` search type has been deprecated. All benefits from this search
type can now be achieved by doing a scroll request that sorts documents in
`_doc` order, for instance:

[source,sh]
---------------
GET /my_index/_search?scroll=2m
{
  "sort": [
    "_doc"
  ]
}
---------------

Scroll requests sorted by `_doc` have been optimized to more efficiently resume
from where the previous request stopped, so this will have the same performance
characteristics as the former `scan` search type.

=== Mapping changes

==== position_offset_gap
The default `position_offset_grap` is now 100. Indexes created in Elasticsearch
2.1.0 will default to using 100 and indexes created before that will continue
to use the old default of 0. This was done to prevent phrase queries from
matching across different values of the same term unexpectedly. Specifically,
100 was chosen to cause phrase queries with slops up to 99 to match only within
a single value of a field.