Querying an alias throws off scoring completely?

Elastic Stack Elasticsearch
1

Hey all!

I’m seeing some really weird behaviour around index aliases, maybe I’m doing something conceptually dumb.

We have two indexes of very different size (example: 4mn docs in entities-a and 2(!) docs in entities-b ), which both point to an alias, entities.

Now when I query entities for a query that perfectly matches one of the 2 docs in entities-b, I get junk results from entities-a instead. If I remove entities-a from the alias, the query returns the doc from entities-b properly.

The sense I’m getting is that the imbalance of the indexes completely throws off relevancy scoring - is that likely? Is there any way to address it?

2

Hi,

If you want to prioritize results from entities-b over entities-a , you can use the indices_boost parameter in your search query.

Regards

3

Thanks for that hint! While that may be a possible work-around, I would like to understand the problem a bit more before hacking it. The thing is that the match in entities-b is a perfect result (unique match on a boosted keyword field), so it should come out on top even if both indexes are queried...

4

Have you tried setting the search_type query parameter to dfs_query_then_fetch? Does that make any difference?

1 Like
5

That looks to have made a difference!! My sample queries are coming back with the correct doc now. Is this safe to do? Does it point to an underlying issue, or is it just a little price we'll have to pay for this whacky setup?

6

Yes. It is a different query mode especially designed for better handling shards with different sizes and distributions of data.

No, not really. Have a look at the docs and the links therein to distributes term frequences and relevancy scoring.

1 Like
7

Thank you very much for your competent help, @Christian_Dahlqvist! Appreciate you taking the time.

8

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