```
SELECT version()
─version()─┐
│ 21.8.5.7  │
└───────────┘
```
We have a request, as a result of which we get an array.
When getting an item using a computed value, there is no value
```
SELECT
    arrayMap(x -> x, [[1], [2], [3]]) AS x,
    toTypeName(x),
    x[3 - 2] AS y,
    x[toInt64(1)] AS yy,
    x[toUInt8(1)] AS yyy

┌─x─────────────┬─toTypeName(arrayMap(lambda(tuple(x), x), [[1], [2], [3]]))─┬─y──┬─yy─┬─yyy─┐
│ [[1],[2],[3]] │ Array(Array(UInt8))                                        │ [] │ [] │ [1] │
└───────────────┴────────────────────────────────────────────────────────────┴────┴────┴─────┘
```
However, when the array is explicitly specified, the value is present.
The types are the same.
```
SELECT
    [[1], [2], [3]] AS x,
    toTypeName(x),
    x[3 - 2] AS y,
    x[toInt64(1)] AS yy,
    x[toInt8(1)] AS yyy

┌─x─────────────┬─toTypeName([[1], [2], [3]])─┬─y───┬─yy──┬─yyy─┐
│ [[1],[2],[3]] │ Array(Array(UInt8))         │ [1] │ [1] │ [1] │
└───────────────┴─────────────────────────────┴─────┴─────┴─────┘
```


ColumnPtr executeTuple(const ColumnsWithTypeAndName & arguments, size_t input_rows_count) const;
    /** For a map the function finds the matched value for a key.
     *  Currently implemented just as linear search in array.
     *  However, optimizations are possible.
     */
    ColumnPtr executeMap(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, size_t input_rows_count) const;
    using Offsets = ColumnArray::Offsets;
    static bool matchKeyToIndexNumber(
        const IColumn & data, const Offsets & offsets, bool is_key_const,
        const IColumn & index, PaddedPODArray<UInt64> & matched_idxs);
    static bool matchKeyToIndexNumberConst(
        const IColumn & data, const Offsets & offsets,
        const Field & index, PaddedPODArray<UInt64> & matched_idxs);
    static bool matchKeyToIndexString(
        const IColumn & data, const Offsets & offsets, bool is_key_const,
        const IColumn & index, PaddedPODArray<UInt64> & matched_idxs);
    static bool matchKeyToIndexStringConst(
        const IColumn & data, const Offsets & offsets,
        const Field & index, PaddedPODArray<UInt64> & matched_idxs);
    template <typename Matcher>
    static void executeMatchKeyToIndex(const Offsets & offsets,
        PaddedPODArray<UInt64> & matched_idxs, const Matcher & matcher);
    template <typename Matcher>
    static void executeMatchConstKeyToIndex(
        size_t num_rows, size_t num_values,
        PaddedPODArray<UInt64> & matched_idxs, const Matcher & matcher);
};
namespace ArrayImpl
{
class NullMapBuilder