elasticsearch - ElasticSearch:min_doc_count如何影响性能？

Question

为什么要花时间:

"aggs": {
            "Condition": {
                "terms": {
                    "field": "color",
                    "size": 10,
                    "min_doc_count": 1
                }
          }

比这快得多:

    "aggs": {
            "Condition": {
                "terms": {
                    "field": "color",
                    "size": 10,
                    "min_doc_count": 0
                }
          }

即使他们都向我返回了相同的汇总结果？

Answer 1

从documentation中提取:

Setting min_doc_count=0 will also return buckets for terms that didn’t match any hit. However, some of the returned terms which have a document count of zero might only belong to deleted documents or documents from other types, so there is no warranty that a match_all query would find a positive document count for those terms.

因此，如果删除的文档很多，则性能可能会变差，因为聚合将处理大量的文档。尝试 optimize the index看看性能是否变得相似。