This commit adds back "id" as the key within a script to specify a
stored script (which with file scripts now gone is no longer ambiguous).
It also adds "source" as a replacement for "code". This is in an attempt
to normalize how scripts are specified across both put stored scripts and script usages, including search template requests. This also deprecates the old inline/stored keys.
In scripts (at least some of the languages), the terms dictionary and
postings can be access with the special _index variable. This is for
very advanced use cases which want to do their own scoring. The problem
is segment level statistics must be recomputed for every document.
Additionally, this is not friendly to the terms index caching as the
order of looking up terms should be controlled by lucene.
This change removes _index from scripts. Anyone using it can and should
instead write a Similarity plugin, which is explicitly designed to allow
doing the calculations needed for a relevance score.
closes#19359
* Scripting: Remove groovy scripting language
Groovy was deprecated in 5.0. This change removes it, along with the
legacy default language infrastructure in scripting.
* Reorganize scripting documentation
* Further changes to tidy up scripting docs
Closes#18116
* Add note about .lat/lon potentially returning null
* Added .value to expressions example
* Fixed two bad ASCIIDOC links
Ryan Ernst
Nik Everett
Clinton Gormley