CODEWITHSUNDEEP
elasticsearchelasticsearch-aggregation
user1454265
user1454265

Reputation: 878

How to get Elastic Search aggregation to mirror the query filtering logic?

On our site we allow users to filter Elastic Search results with a set of filters divided into categories:

A
  A1
  A2
  ...
B
  B1
  B2
  B3
  ...

These are just matching on literal tags that can appear in a field of the document, like:

{ tags: ["A1", "B1", "B2"] }

Our existing query joins all the filter terms under AND, so if the user selects A1, B1, and B2, we filter by (A1 AND B1 AND B2).

We want to change this to "OR within each filter category", and "AND across categories", so that you'd get: (A1) AND (B1 OR B2).

Now, the wrinkle: we also use a "terms" aggregation on the "tags" field to predict how many items would come back from applying the next filter. On our UI this looks like:

A
  A1   12   # If the user adds the A1 filter, there'll be 12 results.
  A2   3    # etc.
  ...
B
  B1   5
  B2   0
  B3   2
  ...

Here, changing the filter logic to AND/OR breaks the counts that come back from the "terms" aggregation, because the terms aggregation is still predicting A1 AND B1 AND B2. Adding B3 would get us A1 AND B1 AND B2 AND B3 and thus narrow the counts from the aggregations, whereas it would actually widen the scope of the results (we'd want (A1) AND (B1 OR B2 OR B3)).

Is there a way to express this in aggregations so that the filtering logic and the aggregation counts match?

Upvotes: 1

Views: 224

Answers (1)

Andreas Jägle
Andreas Jägle

Reputation: 12260

You can use the Filter aggregation that constructs buckets based on anything you could also use as filters in a regular query. This can work if you are able to construct the filters beforehand and there are not too many possible values because you would need to define one filter bucket for each "next" combination. Please be aware that this could have performance implications when compared with a simple Terms aggregation.

For details please see the docs at: https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-filter-aggregation.html

Upvotes: 2

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