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slug | sidebar_position |
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/en/sql-reference/aggregate-functions/reference/grouparray | 110 |
groupArray
Syntax: groupArray(x)
or groupArray(max_size)(x)
Creates an array of argument values. Values can be added to the array in any (indeterminate) order.
The second version (with the max_size
parameter) limits the size of the resulting array to max_size
elements. For example, groupArray(1)(x)
is equivalent to [any (x)]
.
In some cases, you can still rely on the order of execution. This applies to cases when SELECT
comes from a subquery that uses ORDER BY
.
Example
SELECT * FROM default.ck;
┌─id─┬─name─────┐
│ 1 │ zhangsan │
│ 1 │ ᴺᵁᴸᴸ │
│ 1 │ lisi │
│ 2 │ wangwu │
└────┴──────────┘
Query:
select id, groupArray(10)(name) from default.ck group by id;
Result:
┌─id─┬─groupArray(10)(name)─┐
│ 1 │ ['zhangsan','lisi'] │
│ 2 │ ['wangwu'] │
└────┴──────────────────────┘
The groupArray function will remove ᴺᵁᴸᴸ value based on the above results.