I need, for each document I index, to store the exact currency conversion rates that apply when the document was index. My first naïve idea was to index, along the documents, the list of all conversion rates relative to the currency of the indexed document. However, I realize that it can quickly lead to large indices because of the massive duplication of data, but I cannot see any other way to do that.
Any idea about how I could address that in a more efficient way?
(also: the currency rates are then used in a script Expression for aggregations. To that extent, is it better to store currency rates as doc_values or standard fields?)