How to search aggregations in ES?

Elastic Stack Elasticsearch
1

I have a books index which contains an array of tags (with both text/keyword types), i'd like to offer an autocomplete for tags so users type "ro" and it returns "romance" or "rock and roll".

Here's my mapping:

/books {
 ...
  tags: {
    type: 'text',
    field: {
      keyword: {type: 'keyword'}
    }
  }
}

Example book

{ name: "foo", tags: ['romance', 'story', 'fiction'] }

My aggregation for tags:

      {
      size: 0,
      aggregations: {
        options: {
          terms: {
            field: `tags.keyword`,
            size: 20
          }
        }
      }

The problem is i get other tags not containing "ro" but they simply happened to be in same documents that have other "ro" tags

How can I only get all distinct tags that match "ro"?

2

This is not entirely trivial to do with the aggregations API. Have you considered using the completion suggester instead? It was designed for this exact use case.

3

Is it better to use completion suggester or Edge ngrams tokenizer for autocomplete process?

4

The advantage of the completion suggester is that it will load the suggestions in memory. As a result, the suggestions will be returned really quickly; typically faster than a query using edge ngrams would do.

5

I failed using Highlighting in Completion Suggestion, Comparison of different methods for autocompletion also mentions that Completion Suggester fails to support Highlighting. Is there a way to overcome this issue?

6

I don't think the completion suggester supports highlighting. If you need that, you may be better off with a search-based approach.

1 Like
7

Edge ngram fails to suggest when searching with terms containing symbols. I know whitespace analyzer will solve this issue while using it in different query. how do i mention "whitespace" tokenizer within edge ngram custom analyzer.

8

The documentation has an example of how to configure a custom analyzer: https://www.elastic.co/guide/en/elasticsearch/reference/current/analysis-custom-analyzer.html#_example_configuration_5

Just replace "tokenizer": "standard" in that example with "tokenizer": "whitespace" (and of course apply the filters that you want to use instead of those in the example).

9

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