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

**Description**

Converts a multivalued expression into a single valued column containing the first value. This is most useful when reading from a function that emits multivalued columns in a known order like [`SPLIT`](/reference/query-languages/esql/esql-functions-operators.md#esql-split).

The order that [multivalued fields](/reference/query-languages/esql/esql-multivalued-fields.md) are read from
underlying storage is not guaranteed. It is **frequently** ascending, but don’t
rely on that. If you need the minimum value use [`MV_MIN`](/reference/query-languages/esql/esql-functions-operators.md#esql-mv_min) instead of
`MV_FIRST`. `MV_MIN` has optimizations for sorted values so there isn’t a
performance benefit to `MV_FIRST`.