ES|QL: Add MV_INTERSECTION Function

[markjhoy]

Adds MV_INTERSECTION function to ES|QL.

Returns a subset of the inputs sets that contains the intersection of values in provided multi-valued arguments.

Example:

Given set A = {"a","b","c"} and set B = {"b","c","d"}
MV_INTERSECTION(A, B) returns {"b", "c"}

[github-actions]

🔍 Preview links for changed docs

• docs/reference/query-languages/esql/kibana/docs/functions/mv_intersection.md
• docs/reference/query-languages/esql/functions-operators/mv-functions.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.

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[elasticsearchmachine]

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

[elasticsearchmachine]

Pinging @elastic/es-analytical-engine (Team:Analytics)

[elasticsearchmachine]

Pinging @elastic/search-eng (Team:SearchOrg)

[markjhoy]

Just to doublecheck - are the tags here correct? (Preview for 9.3.0?)

[leemthompo]

LGTM!

[kderusso]

Changes LGTM, will defer to Ioana to approve after her feedback is met. Thanks!

[kderusso]

Any tests needed for null input, etc?

[markjhoy]

There's one at least in the IT tests ({null, null} -> {null}) as well as others that check for null as the first or second argument - so, I don't think it needs to be in the verifier... however the validation is going to change a bit from Ioana's suggestions...

[craigtaverner]

When comparing this with the geospatial functions, I would naturally think this function should be called MV_INTERSECTION, because the term MV_INTERSECT sounds too much like it should return a boolean.

Class	Operation	Spatial	MV/List/Array
Predicate	Intersects	ST_INTERSECTS	MV_INTERSECTS
Predicate	Contains	ST_CONTAINS	MV_CONTAINS
Set	Intersection	ST_INTERSECTION	MV_INTERSECTION

[craigtaverner]

I think we need to re-think the name. I propose MV_INTERSECTION both to better match set-theory as well as better symmetry with related GIS functions.

[ioanatia]

When comparing this with the geospatial functions, I would naturally think this function should be called MV_INTERSECTION, because the term MV_INTERSECT sounds too much like it should return a boolean.

@craigtaverner that makes sense to change it to MV_INTERSECTION - we just took the name from #98545 and we assumed it was the right name

[markjhoy]

Good call @craigtaverner - I'll refactor, and I've also updated the meta issue as well to reflect this.

[craigtaverner]

Good call @craigtaverner - I'll refactor, and I've also updated the meta issue as well to reflect this.

Thanks! Great that you fixed the meta-issue too. Sometimes those issues are just a first guess as to what we need, so always good to second-guess! 😄

[craigtaverner]

Much nicer with the name change!

[leemthompo]

Thanks for iterating on the docs! One tiny little thing left to add: an inline applies_to tag in the list :)

[markjhoy]

Thanks for iterating on the docs! One tiny little thing left to add: an inline applies_to tag in the list :)

All set. Thanks for your help!

[markjhoy]

buildkite test this