OpenSearch/docs/reference/migration/migrate_1_x.asciidoc

[[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.

==== Indices APIs

The <<warmer-retrieving, get warmer api>> will return a section for `warmers` even if there are 
no warmers.  This ensures that the following two examples are equivalent:

[source,js]
--------------------------------------------------
curl -XGET 'http://localhost:9200/_all/_warmers'

curl -XGET 'http://localhost:9200/_warmers'
--------------------------------------------------

The <<alias-retrieving, get alias api>> will return a section for `aliases` even if there are 
no aliases.  This ensures that the following two examples are equivalent:

[source,js]
--------------------------------------------------
curl -XGET 'http://localhost:9200/_all/_aliases'

curl -XGET 'http://localhost:9200/_aliases'
--------------------------------------------------

In addition, the <<alias-retrieving, get alias api>> now supports <<multi-index>> options and, by default, will
produce an error response if a requested index does not exist.

The <<indices-get-mapping, get mapping api>> will return a section for `mappings` even if there are 
no mappings.  This ensures that the following two examples are equivalent:

[source,js]
--------------------------------------------------
curl -XGET 'http://localhost:9200/_all/_mappings'

curl -XGET 'http://localhost:9200/_mappings'
--------------------------------------------------