How to get the list of all available fields in a (sharded) index

[olivier sallou]

Hi,
I cannot find any info on how to get the list of current fields in an index
(possibly sharded). With dynamic fields, I cannot simply parse the schema to
know what field are available.
Is there any way to get it via a request (or easilly programmable) ? I know
information is available in one of the Lucene generated files, but I 'd like
to get it via a query for my whole index.

Thanks

Olivier