I was trying to index a "keyword" datatype field by its reversal in a multi-field mapping but it seems that the reverse token filter is not allowed in a normalizer.
I wanted to enable a "suffix query" (ends with) without the search performance penalty of using a wildcard query with a starting '*'. With the reversed "keyword" indexed, it is then possible to use the prefix query for an efficient suffix query.
Currently I'm working around the restriction on the normalizer by using a custom analyzer on the "text" datatype using the keyword tokenizer, but if it is possible to use a normalizer that would be preferred.
The docs say
Only the filters that work on a per-character basis are allowed
Can someone confirm if the reverse token filter meets that requirement or not? I would think that a reverse operation could work on a per-character basis.