Adds formal API docs for the following APIs:
* Clear SQL cursor
* SQL search
* SQL translate
Other changes:
* Removes and redirects the "Supported REST parameters section." This is now covered in the SQL search API docs.
* Updates a few related xrefs.
Closes#75085
Moving towards grouping of data types in the field caps API
the internal data type `DATETIME_NANOS` introduced for `date_nanos`
support is eliminated.
Relates: #67722
Follows: #67666
* Integrate "fields" API into QL (#68467)
* QL: retry SQL and EQL requests in a mixed-node (rolling upgrade) cluster (#68602)
* Adapt nested fields extraction from "fields" API output to the new un-flattened structure (#68745)
* Switch from using docvalue_fields to extracting values from _source
where applicable. Doing this means parsing the _source and handling the
numbers parsing just like Elasticsearch is doing it when it's indexing
a document.
* This also introduces a minor limitation: aliases type of fields that
are NOT part of a tree of sub-fields will not be able to be retrieved
anymore. field_caps API doesn't shed any light into a field being an
alias or not and at _source parsing time there is no way to know if a
root field is an alias or not. Fields of the type "a.b.c.alias" can be
extracted from docvalue_fields, only if the field they point to can be
extracted from docvalue_fields. Also, not all fields in a hierarchy of
fields can be evaluated to being an alias.
Doc-value fields now return a value that is based on the mappings rather than
the script implementation by default.
This deprecates the special `use_field_mapping` docvalue format which was added
in #29639 only to ease the transition to 7.x and it is not necessary anymore in
7.0.
Make SQL aware of missing and/or unmapped fields treating them as NULL
Make _all_ functions and operators null-safe aware, including when used
in filtering or sorting contexts
Add missing and null-safe doc value extractor
Modify dataset to have null fields spread around (in groups of 10)
Enforce missing last and unmapped_type inside sorting
Consolidate Predicate templating and declaration
Add support for Like/RLike in scripting
Generalize NULLS LAST/FIRST
Introduce early schema declaration for CSV spec tests: to keep the doc
snippets in place (introduce schema:: prefix for declaration)
upfront.
Fix#32079
James Rodewig
Marios Trivyzas
Andrei Stefan
James Rodewig
Costin Leau
Adrien Grand
Jason Tedor
Lisa Cawley