risingwave_expr_impl/scalar/
cardinality.rs

1// Copyright 2025 RisingWave Labs
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15use risingwave_common::array::ListRef;
16use risingwave_expr::{ExprError, Result, function};
17
18/// Returns the total number of elements in the array.
19///
20/// ```sql
21/// cardinality ( array anyarray) → int8
22/// ```
23///
24/// Examples:
25///
26/// ```slt
27/// query T
28/// select cardinality(null::int[]);
29/// ----
30/// NULL
31///
32/// query T
33/// select cardinality(array[1,2,3]);
34/// ----
35/// 3
36///
37/// query T
38/// select cardinality(array[1,2,3,4,1]);
39/// ----
40/// 5
41///
42/// query T
43/// select cardinality(array[array[1, 2, 3]]);
44/// ----
45/// 3
46///
47/// query T
48/// select cardinality(array[array[array[3,4,5],array[2,2,2]],array[array[6,7,8],array[0,0,0]]]);
49/// ----
50/// 12
51///
52/// query T
53/// select cardinality(array[NULL]);
54/// ----
55/// 1
56///
57/// query error Cannot implicitly cast
58/// select cardinality(null);
59/// ```
60#[function("cardinality(anyarray) -> int4")]
61#[function("cardinality(anyarray) -> int8", deprecated)]
62fn cardinality<T: TryFrom<usize>>(array: ListRef<'_>) -> Result<T> {
63    array
64        .flatten()
65        .len()
66        .try_into()
67        .map_err(|_| ExprError::NumericOverflow)
68}
risingwave_expr_impl/scalar/cardinality.rs

risingwave_expr_impl/scalar/
cardinality.rs
