* ESQL: change from quoting from backtick to quote
For historical reasons, the source declaration inside FROM command is
treated as an identifier, using backticks (`) for escaping the value.
This is inconsistent since the source is not an identifier (field name)
but an index name which has different semantics.
`index` means a field name index while "index" means a literal with
said value.
In case of FROM, the index name/location is more like a literal (also in
unquoted form) than an identifier (that is a reference to a value).
This PR tweaks the grammar and plugs in the quoted string logic so that
both the single quote (") and triple quote (""") are allowed.
* Update grammar
* Add more tests
* Add a few more tests
* Add extra test
* Update docs/changelog/108395.yaml
* Adress review comments
* Add doc note
* Revert test rename
* Fix quoting with remote cluster
* Update docs/reference/esql/source-commands/from.asciidoc
Co-authored-by: marciw <333176+marciw@users.noreply.github.com>
---------
Co-authored-by: Bogdan Pintea <bogdan.pintea@elastic.co>
Co-authored-by: Bogdan Pintea <pintea@mailbox.org>
Co-authored-by: marciw <333176+marciw@users.noreply.github.com>
Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>
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