We are about to stand up a time series datastream for some metrics data that we've been tracking via multiple indices. One of the notes on the TSDS documentation page suggests that you should only use a TSDS "if you typically add metrics data to Elasticsearch in near real-time and @timestamp order.
That will be the case moving forward. However, we have some historical data that we want to include. It needs to be re-ingested (via a script (of that matters), not a reindex, since the data structure needs to be changed). This is on the order of 10 million documents. Is this going to cause an issue?