[Core] Support for Aggregations

[alexander-schranz]

Typical shops will allow if you search something that they show categories to add additional filters. In that case mostly only categories are shown which matches the current search condition of the user. This kind of things are called aggregations.

There are different kind of aggregations which would be nice to support but requires a lot of research if all kind of currently supported search engines support such kind of aggregations:

• category filter aggregations (matching categories with search term)
• price range filter aggregations (lowest and highest price)

Questions:

What kind of search engines support this kind of aggregations

Supported:

• Elasticsearch / Opensearch (https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-terms-aggregation.html @wachterjohannes maybe you can show how currently this was done in such projects)

Maybe:

• RediSearch (not tested yet (https://redis.io/docs/stack/search/reference/aggregations/)
• Algolia (not tested yet (https://www.algolia.com/doc/guides/managing-results/refine-results/faceting/#retrieving-facets))
• Meilisearch (not tested yet (https://www.meilisearch.com/docs/learn/advanced/faceted_search#facet-distribution))
• Solr (not tested yet (https://solr.apache.org/guide/8_8/search-sample.html#facet))
• Typesense ( not tested yet (https://typesense.org/docs/0.24.1/api/search.html#facet-results))

Should aggregations be part of the search result or own call?

Some search engines support aggregations as combination with the search query, some already requires that the aggregation is a seperate query. Not sure what from the DX point if SearchBuilder allows to query aggregations or if a seperate AggregationBuilder would be better and provide easier DX.

Which type of aggregations are required?

• Term Aggregation? (e.g.: category filter)
• Min/Max Aggregation? (e.g.: price range filter)
• Average Aggregation (show average price value)
• ...? What other aggregations exists?

[alexander-schranz]

@Toflar do you have anything planned to support aggregations for @loupe-php?

[Toflar]

I have no plans for nothing :) Loupe will be what people make it :)