Antonio Matarrese 79c7a57737 Use the breadth first collection mode for significant terms aggs. (#29042)
This helps avoid memory issues when computing deep sub-aggregations. Because it
should be rare to use sub-aggregations with significant terms, we opted to always
choose breadth first as opposed to exposing a `collect_mode` option.

Closes #28652.
2019-04-11 15:56:02 -07:00
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2017-12-14 17:47:53 +01:00