Is it normal or a bug that same query has the result with different score?

Elastic Search
1

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I'm working on a project using elk search. I need consistant score of query result for the purpose of consistant search_after result. However, the score is not consistant given the same query, same index, no change to the index.

Have u came across the same issue?

I'm wondering:

  1. Is the score inherently inconsistant for elk? or is this some bug?
  2. Is just the absolute score inconsistant? what about the relative score? I mean the ranking/sorting of all query hits would be consistant or inconsistant?

Notes: The score is generated by a sole match_phrase clause and the version is 8.16.1. This database does not have writing for a while.

2

What do you see in explain mode? It may be useful to compare it side-by-side when final scores are different

POST _search?explain=true
{
  "query": {
<...>
  }
}
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3

Thank u for the suggestion, it's helpful!

I used the explain mode and compare, it looks tf/idf calculation uses different ifd statistics, not sure if it is because different shards responded to the search (we have one primary and one secondary)

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4

Does any one know the source of inconsistency?

FYI, the structure of my elk structure is: 3 cluster, 12 shards, each shard has two copies.

I look at one particular result and this result resides in one shard (one primary and one secondary) exactly

5

Yes. That's most likely the case here.

What happens if you are using dfs_query_then_fetch for search_type? See Search API | Elasticsearch Guide [8.17] | Elastic

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