Partial highlighting when using Atlas Search autocomplete

H_R1 · 2025-01-21T12:50:22.384Z

I’m considering migrating our Algolia search database to Atlas. I’ve read through most (all?) of the relevant documentation and I’m either missing/misunderstanding how to highlight properly or it’s a missing feature that Mongo Atlas cannot replicate. If anyone can clarify then thank you in advance.

Relevant documentation: https://www.mongodb.com/docs/atlas/atlas-search/autocomplete/#highlighting-example

This shows that the example query results have the entire ‘path’ highlighted. The issue with this is that highlighting everything is as effective as highlighting nothing:

Example query of ‘Ger’ from the docs:

image1620×1842 310 KB

Is there a way to get just the ‘Ger’ as a highlight ‘hit’. E.g. of expected result (that could be shown in the UI to the user in a helpful way):

{
	"title": "Gertie the Dinosaur",
	"score": 6.0822906494140625,
	"highlights": [
		{
			"score": 0.9227690100669861,
			"path": "title",
			"texts": [
        { "value": "Ger", "type": "hit" },
        { "value": "tie the Dinosaur", "type": "text" }
      ]
		}
	]
}

Again, thanks in advance for any guidance/help.

amyjian · 2025-01-24T17:24:26.859Z

Hi @H_R1 , this is the expected behavior when highlighting on autocomplete paths today – the returned “hits” will be at least maxGrams in length. We are aware that this is not ideal, and would like to improve this in the future. I suggest opening a feedback item in our portal here to track improvements.

That being said, you can play around with a custom analyzer that mimics autocomplete search behavior while retrieving partial word highlights – example here. You can configure the tokenizer, maxGram and minGram in the custom analyzer like you would for an autocomplete type.

Let me know if this helps!