Regarding updating documents via Elasticsearch's bulk API, how are documents compared? As far as I know, for the "Create" action type the index will fail if index and type exists, and for the "Index" action type the index is deleted then reindexed. Are these documents compared by index name and ID, or is the entire document compared using a hash function or something similar? Is the same comparisons used for update/partial update APIs?
If it is a hash function to compare documents, do the meta-fields factor in the equation?