Add TOP_SNIPPETS function to return the best snippets for a field

[kderusso]

Adds a TOP_SNIPPETS function to return the best snippets for a field.

Example usage:

EVAL snippets = TOP_SNIPPETS(description, "Tolkien", { "num_snippets": 3, "num_words": 25 })

[github-actions]

🔍 Preview links for changed docs

• docs/reference/query-languages/esql/kibana/docs/functions/top_snippets.md

[github-actions]

ℹ️ Important: Docs version tagging

👋 Thanks for updating the docs! Just a friendly reminder that our docs are now cumulative. This means all 9.x versions are documented on the same page and published off of the main branch, instead of creating separate pages for each minor version.

We use applies_to tags to mark version-specific features and changes.

Expand for a quick overview

When to use applies_to tags:

✅ At the page level to indicate which products/deployments the content applies to (mandatory)
✅ When features change state (e.g. preview, ga) in a specific version
✅ When availability differs across deployments and environments

What NOT to do:

❌ Don't remove or replace information that applies to an older version
❌ Don't add new information that applies to a specific version without an applies_to tag
❌ Don't forget that applies_to tags can be used at the page, section, and inline level

🤔 Need help?

• Check out the cumulative docs guidelines
• Reach out in the #docs Slack channel

[elasticsearchmachine]

Hi @kderusso, I've created a changelog YAML for you.

[elasticsearchmachine]

Pinging @elastic/es-search-relevance (Team:Search Relevance)

[ioanatia]

looks on the right track

[benwtrent]

We need to be clear what kind of query this actually is. Query string seems like qstr but it isn't. Is this a match query? Is it qstr? Is it just a term query? Does it accept wildcards?

[kderusso]

Updated the docs, LMKWYT

[benwtrent]

looks ok to me. ESQL experts should review of course.

[carlosdelest]

Looks great! 🎉

We need to support NULL as a field, so we don't error out for multi index queries. Once that's done this is ready to go from my side.

Some other minor comments.

[carlosdelest]

LGTM 👍