* Add release notes for 7.0.0-rc1.
* [DOCS] Fixes broken link to breaking changes
* [DOCS] Removed old ML PRs; edited titles
* Remove superseded PR.
* Clean up Lucene upgrade PRs/issues.
We were missing release notes for 7.0.0-alpha1. I generated them by running
the release-notes script with a quick hack that filtered out pull requests
that had been closed on or after 2018-11-15.
Some breaking changes had been documented in the release notes rather than
the migration guide so I moved them.
With this commit we differentiate between permanent circuit breaking
exceptions (which require intervention from an operator and should not
be automatically retried) and transient ones (which may heal themselves
eventually and should be retried). Furthermore, the parent circuit
breaker will categorize a circuit breaking exception as either transient
or permanent based on the categorization of memory usage of its child
circuit breakers.
Closes#31986
Relates #34460
Suggestion responses were previously serialized as streamables which
made writing suggesters in plugins with custom suggestion response types
impossible. This commit makes them serialized as named writeables and
provides a facility for registering a reader for suggestion responses
when registering a suggester.
This also makes Suggestion responses abstract, requiring a suggester
implementation to provide its own types. Suggesters which do not need
anything additional to what is defined in Suggest.Suggestion should
provide a minimal subclass.
The existing plugin suggester integration tests are removed and
replaced with an equivalent implementation as an example
plugin.
The other metric aggregations (min/max/etc) return `null` as their XContent value and string when nothing was computed (due to empty/missing fields). Percentiles and Percentile Ranks, however, return `NaN `which is inconsistent and confusing for the user. This fixes the inconsistency by making the aggs return `null`. This applies to both the numeric value and the "as string" value.
Note: like the metric aggs, this does not change the value if fetched directly from the percentiles object, which will return as `NaN`/`"NaN"`. This only changes the XContent output.
While this is a bugfix, it still breaks bwc in a minor way as the response changes from prior version.
Closes#29066
Clearing the cache indices can be done via GET and POST. As GET should
only support read only operations, this removes the support for using
GET for clearing the indices caches.