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Map functions ​

Map functions operate on typed, ordered key/value pairs. Duplicate keys remain present; a lookup selects the first matching pair.

Functions ​

Function Result
map(key, value, ...) A map constructed from alternating keys and values.
map_keys(map) An array of keys in pair order, including duplicates.
map_values(map) An array of values in pair order.
map_element(map, key) The first matching value, or the value type's default.
map_contains(map, key) A Bool indicating whether the key occurs.

Keys cannot be NULL. Typed map declarations validate every key and value. A missing key and a stored default can return the same value; use map_contains to distinguish them.

Examples ​

Duplicate keys ​

sql
SELECT map_keys(map('a', 1, 'a', 2)),
       map_values(map('a', 1, 'a', 2)),
       map_element(map('a', 1, 'a', 2), 'a')
FORMAT csv;
text
"[""a"",""a""]","[1,2]",1

A stored default and a missing key ​

sql
SELECT map_element(map('views', 0), 'views'),
       map_contains(map('views', 0), 'views'),
       map_element(map('views', 0), 'likes'),
       map_contains(map('views', 0), 'likes')
FORMAT csv;
text
0,true,0,false

See the Map type for JSON input, value defaults and nullable values.