MAP_KEYS

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Syntax

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Scalar

map_keys(map)

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Arguments

• K is the map key type: BOOLEAN, TINYINT, SMALLINT, INTEGER, BIGINT, FLOAT, DOUBLE, DECIMAL(p, s), STRING, BINARY, DATE, TIME, TIMESTAMP, ARRAY, MAP or STRUCT.

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Returns

• Type: ARRAY<K>
• Possible values: One key per map entry.
• NULL behavior: Returns NULL for a NULL map.
• Shape: Array length equals map entry count.
• Ordering: Underlying map entry order; no key sorting is performed.

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Properties

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Usage notes

• INTEGER and INT mean the same type; STRING means VARCHAR text. NULL can be used with a supported type. Cast NULL explicitly when its type would otherwise be unclear.
• For ARRAY-valued keys or values, construct the input map with MAP_FROM_ARRAYS. The ordinary two-argument MAP constructor can interpret ARRAY arguments as parallel key/value lists.

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Examples

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Typical behavior

SELECT map_keys(map_from_arrays(ARRAY['a', 'b'], ARRAY[1, NULL])) AS "value";

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Integer map keys

SELECT map_keys(map(10, 'red', 20, 'blue')) AS keys;