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2.1 KiB
2.1 KiB
slug | sidebar_position |
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/en/sql-reference/aggregate-functions/reference/topkweighted | 109 |
topKWeighted
Returns an array of the approximately most frequent values in the specified column. The resulting array is sorted in descending order of approximate frequency of values (not by the values themselves). Additionally, the weight of the value is taken into account.
Syntax
topKWeighted(N)(column, weight)
topKWeighted(N, load_factor)(column, weight)
topKWeighted(N, load_factor, 'counts')(column, weight)
Parameters
N
— The number of elements to return. Optional. Default value: 10.load_factor
— Defines, how many cells reserved for values. If uniq(column) > N * load_factor, result of topK function will be approximate. Optional. Default value: 3.counts
— Defines, should result contain approximate count and error value.
Arguments
column
— The value.weight
— The weight. Every value is accountedweight
times for frequency calculation. UInt64.
Returned value
Returns an array of the values with maximum approximate sum of weights.
Example
Query:
SELECT topKWeighted(2)(k, w) FROM
VALUES('k Char, w UInt64', ('y', 1), ('y', 1), ('x', 5), ('y', 1), ('z', 10))
Result:
┌─topKWeighted(2)(k, w)──┐
│ ['z','x'] │
└────────────────────────┘
Query:
SELECT topKWeighted(2, 10, 'counts')(k, w)
FROM VALUES('k Char, w UInt64', ('y', 1), ('y', 1), ('x', 5), ('y', 1), ('z', 10))
Result:
┌─topKWeighted(2, 10, 'counts')(k, w)─┐
│ [('z',10,0),('x',5,0)] │
└─────────────────────────────────────┘
See Also