Add ES|QL signum function

[ioanatia]

#98545

Implements the signum function.

PUT testidx
{
  "mappings": {
    "properties": {
      "float_field": {
        "type": "float"
      }
    }
  }
}

POST testidx/_doc
{ "float_field": 25 }

POST testidx/_doc
{ "float_field": -100.0 }

POST testidx/_doc
{ "float_field": 0 }

POST testidx/_doc
{ "float_field": null }


POST _query
{
  "query": """
  FROM testidx|
  EVAL s = signum(float_field)
  """
}

result:

{
  "columns": [
    {
      "name": "float_field",
      "type": "double"
    },
    {
      "name": "s",
      "type": "double"
    }
  ],
  "values": [
    [
      25,
      1
    ],
    [
      -100,
      -1
    ],
    [
      0,
      0
    ],
    [
      null,
      null
    ]
  ]
}

[github-actions]

Documentation preview:

• ✨ Changed pages

[elasticsearchmachine]

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

[elasticsearchmachine]

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

[nik9000]

I've been leaning towards putting these in floats.csv-spec and ints.csv-spec and unsigned_long.csv-spec.

[ioanatia]

Done - and in this case, I also don't need to add #[skip:-8.13.99,reason:new scalar function added in 8.14]?
doesn't seem like it from the other specs in these files.

[nik9000]

If it's new I believe you still need it. I believe we'll be transitioning these to the "features" APIs before too long, but that's half way through at the moment so I'd stick with the skips.

You have to run something like ./gradlew -p x-pack/plugin/esql/qa/server/mixed-cluster v8.13.1#bwcTest to bump into it.

[nik9000]

If you link to this file in math-functions.asciidoc then we'll render the generated docs.

[nik9000]

Would you mind updating the package-info.java file with instructions to do this? I should have done it when I wrote the code generation, but I forgot.

[ioanatia]

Done and done! the package-info.java instructions are great btw!

[astefan]

Thank you for your contribution.

Having csv-spec tests that only use row is not enough.
Take a look at other csv-spec files where from command is used and try to have more complex queries with nested functions, using the signum function in all other commands (sort, eval, filter, stats etc).

[nik9000]

Having csv-spec tests that only use row is not enough.

Ah! I should have caught that one.

the feedback has been addressed.

[ioanatia]

@astefan - more tests have been added and Nik reviewed the PR again yesterday.
I merged it since I wanted to avoid any new merge conflicts, but if there is any additional feedback from you let me know.