We are currently upgrading our system from ElasticSearch 6.8.8 to ElasticSearch 7.17. When we run pageable queries using the Java Rest API, the results are incorrect. For example, in version 6.8.8, if we query for data with and request page 2 with a page size of 10, the query return the 10 items on page 2 and give us a totalElement of 10000 records which is correct. When we run this same exact query on Version 7.17, it returns 10 items on page 2 but only gives us a totalElement of 10 instead of the correct number. We need the correct number, so that our gridview handles paging correctly. Is there a setting I am missing in ElasticSearch version 7.17?
1 Answers
Elasticsearch implemented an option of Track_total_hits in all search in ES 7.X.
Generally the total hit count can’t be computed accurately without visiting all matches, which is costly for queries that match lots of documents. The track_total_hits parameter allows you to control how the total number of hits should be tracked. Given that it is often enough to have a lower bound of the number of hits, such as "there are at least 10000 hits", the default is set to 10,000. This means that requests will count the total hit accurately up to 10,000 hits. It is a good trade-off to speed up searches if you don’t need the accurate number of hits after a certain threshold.
So to force ES to calculate all the hit documents you should set Track_total_hits to true. For more information, you can check the ES official documentation page here.
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