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`MV_SLICE` is useful, but loading values from lucene frequently sorts them so `MV_SLICE` is not as useful as you think it is. It's mostly for after, say, a `SPLIT`. This documents that and adds a link to the section on multivalues. It also moves similar docs to a separate paragraph in the docs for easier reading.
11 lines
679 B
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11 lines
679 B
Text
Generated
// This is generated by ESQL's AbstractFunctionTestCase. Do no edit it. See ../README.md for how to regenerate it.
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*Description*
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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 <<esql-split>>.
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The order that <<esql-multivalued-fields, multivalued fields>> are read from
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underlying storage is not guaranteed. It is *frequently* ascending, but don't
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rely on that. If you need the minimum value use <<esql-mv_min>> instead of
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`MV_FIRST`. `MV_MIN` has optimizations for sorted values so there isn't a
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performance benefit to `MV_FIRST`.
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