In Elasticsearch, which is based on Lucene, each document has an indexed _id field that uniquely identifies it. When Elasticsearch use the _id field to find a document from Lucene, Lucene have to check all the segments of the index. When the values of the _id field are very sequentially, the performance is optimizable.
Since Lucene stores min/maxTerm metrics for each segment and field, we can use those metrics to optimise performance of Lucene look up API. When calling SegmentTermsEnum.seekExact() to lookup an term in an index, we can check whether the term fall in the range of minTerm and maxTerm, so that we can skip some useless segments as soon as possible.
This improvement is beneficial to ES read/write API and Lucene look up API.