OpenSearch/docs/reference/migration/migrate_7_0/api.asciidoc

[[breaking_70_api_changes]]
=== Breaking API changes in 7.0

==== Camel case and underscore parameters deprecated in 6.x have been removed
A number of duplicate parameters deprecated in 6.x have been removed from
Bulk request, Multi Get request, Term Vectors request, and More Like This Query
requests.

The following camel case parameters have been removed:

* `opType`
* `versionType`, `_versionType`

The following parameters starting with underscore have been removed:

* `_parent`
* `_retry_on_conflict`
* `_routing`
* `_version`
* `_version_type`

Instead of these removed parameters, use their non camel case equivalents without
starting underscore, e.g. use `version_type` instead of `_version_type` or `versionType`.

==== Thread pool info

In previous versions of Elasticsearch, the thread pool info returned in the
<<cluster-nodes-info,nodes info API>> returned `min` and `max` values reflecting
the configured minimum and maximum number of threads that could be in each
thread pool. The trouble with this representation is that it does not align with
the configuration parameters used to configure thread pools. For
<<modules-threadpool,scaling thread pools>>, the minimum number of threads is
configured by a parameter called `core` and the maximum number of threads is
configured by a parameter called `max`. For <<modules-threadpool,fixed thread
pools>>, there is only one configuration parameter along these lines and that
parameter is called `size`, reflecting the fixed number of threads in the
pool. This discrepancy between the API and the configuration parameters has been
rectified. Now, the API will report `core` and `max` for scaling thread pools,
and `size` for fixed thread pools.

Similarly, in the cat thread pool API the existing `size` output has been
renamed to `pool_size` which reflects the number of threads currently in the
pool; the shortcut for this value has been changed from `s` to `psz`.  The `min`
output has been renamed to `core` with a shortcut of `cr`, the shortcut for
`max` has been changed to `mx`, and the `size` output with a shortcut of `sz`
has been reused to report the configured number of threads in the pool.  This
aligns the output of the API with the configuration values for thread
pools. Note that `core` and `max` will be populated for scaling thread pools,
and `size` will be populated for fixed thread pools.

==== The parameter `fields` deprecated in 6.x has been removed from Bulk request 
and Update request. The Update API returns `400 - Bad request` if request contains 
unknown parameters (instead of ignored in the previous version).

[[remove-suggest-metric]]
==== Remove support for `suggest` metric/index metric in indices stats and nodes stats APIs

Previously, `suggest` stats were folded into `search` stats. Support for the
`suggest` metric on the indices stats and nodes stats APIs remained for
backwards compatibility. Backwards support for the `suggest` metric was
deprecated in 6.3.0 and now removed in 7.0.0.

[[remove-field-caps-body]]

In the past, `fields` could be provided either as a parameter, or as part of the request
body. Specifying `fields` in the request body as opposed to a parameter was deprecated
in 6.4.0, and is now unsupported in 7.0.0.

==== `copy_settings` is deprecated on shrink and split APIs

Versions of Elasticsearch prior to 6.4.0 did not copy index settings on shrink
and split operations. Starting with Elasticsearch 7.0.0, the default behavior
will be for such settings to be copied on such operations. To enable users in
6.4.0 to transition in 6.4.0 to the default behavior in 7.0.0, the
`copy_settings` parameter was added on the REST layer. As this behavior will be
the only behavior in 8.0.0, this parameter is deprecated in 7.0.0 for removal in
8.0.0.