[[breaking-changes-1.x]]
== Breaking changes in 1.x

This section discusses the changes that you need to be aware of when migrating
your application from Elasticsearch 1.x to Elasticsearch 1.y.

[float]
=== Facets

Facets are deprecated and will be removed in a future release. You are
encouraged to migrate to <<search-aggregations, aggregations>> instead.

[[breaking-changes-1.4]]
=== 1.4

==== Percolator

In indices created with version `1.4.0` or later, percolation queries can only
refer to fields that already exist in the mappings in that index. There are
two ways to make sure that a field mapping exist:

* Add or update a mapping via the <<indices-create-index,create index>> or
  <<indices-put-mapping,put mapping>> apis.
* Percolate a document before registering a query. Percolating a document can
  add field mappings dynamically, in the same way as happens when indexing a
  document.

==== Aliases

<<indices-aliases,Aliases>> can include <<query-dsl-filters,filters>> which
are automatically applied to any search performed via the alias.
<<filtered,Filtered aliases>> created with version `1.4.0` or later can only
refer to field names which exist in the mappings of the index (or indices)
pointed to by the alias.

Add or update a mapping via the <<indices-create-index,create index>> or
<<indices-put-mapping,put mapping>> apis.

