Terms aggregations return up to `size` terms, so up to now, the way to get all
matching terms back was to set `size` to an arbitrary high number that would be
larger than the number of unique terms.
Terms aggregators already made sure to not allocate memory based on the `size`
parameter so this commit mostly consists in making `0` an alias for the
maximum integer value in the TermsParser.
Close#4837
`min_doc_count` is the minimum number of hits that a term or histogram key
should match in order to appear in the response.
`min_doc_count=0` replaces `compute_empty_buckets` for histograms and will
behave exactly like facets' `all_terms=true` for terms aggregations.
Close#4662
When the ValuesSource has ordinals, terms ordinals are used as a cache key to
bucket ordinals. This can make terms aggregations on String terms significantly
faster.
Close#4350
uboness
Adrien Grand
Dawid Weiss