There is the description for INDEXED_VALUE in fields.conf
INDEXED_VALUE = [true|false|<sed-cmd>|<simple-substitution-string>]
* Set this to true if the value is in the raw text of the event.
* Set this to false if the value is not in the raw text of the event.
* Setting this to true expands any search for key=value into a search of
value AND key=value (since value is indexed).
* NOTE: You only need to set indexed_value if indexed = false.
INDEXED_VALUE is used when indexed = false according to the description. Then, when is the option INDEXED_VALUE used? Which circumstances require this option?
Is there a case where only value is indexed and key(field) is not indexed?
The description makes me confused.. Hope anyone help me out.