elasticsearch/docs/reference/esql/functions/description/mv_append.asciidoc

// This is generated by ESQL's AbstractFunctionTestCase. Do no edit it. See ../README.md for how to regenerate it.

*Description*

Concatenates values of two multi-value fields.
ES\|QL: add MV_APPEND function (#107001) Adding `MV_APPEND(value1, value2)` function, that appends two values creating a single multi-value. If one or both the inputs are multi-values, the result is the concatenation of all the values, eg. ``` MV_APPEND([a, b], [c, d]) -> [a, b, c, d] ``` ~I think for this specific case it makes sense to consider `null` values as empty arrays, so that~ ~MV_APPEND(value, null) -> value~ ~It is pretty uncommon for ESQL (all the other functions, apart from `COALESCE`, short-circuit to `null` when one of the values is null), so let's discuss this behavior.~ [EDIT] considering the feedback from Andrei, I changed this logic and made it consistent with the other functions: now if one of the parameters is null, the function returns null 2024-06-05 01:42:29 +08:00			`// This is generated by ESQL's AbstractFunctionTestCase. Do no edit it. See ../README.md for how to regenerate it.`

			`Description`

			`Concatenates values of two multi-value fields.`