I have index A and index B. Index B is a botched reindex of A. Problem is, index B now contains new data I can't lose. So I have documents that are present in A, or B or A&B. I will fix this by running another reindex, with a proper options (skip existing in destination), but I need some form of verification.
I want to query across the two indices, which is easy with Elastic. But I want to get only the documents in index A, which are not present in index B, preferably by ID. I can't quite figure out the query, can anyone help?