We are using ES 1.5 and plan to upgrade to ES 2.x. We store server log files. In a particular type there is a dynamically-created field (field name extracted from the source logs) with dots in it. Since ES 2.0 cannot have fields with dots in them we deleted those offending documents (don't worry, not a loss). However the mapping for that type in the index keeps the mapping for the fields with dots, even though no documents now have that field. We've also updated Logstash to not index dotted fields.
How can I update the type mapping to remove that field so that the index will be compatible with ES 2.0?
If the answer is to reindex the index, how do I do this and will the mappings for the now-unused field be copied too?