Let me rephrase the problem: on the first operation I retrieve a set of documents from multiple shards, on the second operation I retrieve another set of documents which might intersect with the first set that I've just updated.
I need to massively update those documents and my calculations will be wrong if I don't rely on the latest versions of those documents ( from what you suggested, looks like GET will get from the log of the primary shard so the latest version is available, but SEARCH will not as it needs to distribute the search, am I right?)
Thank you for your response