risingwave_frontend/expr/function_impl/
pg_index_column_has_property.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_expr::{Result, capture_context, function};
16
17use super::context::{CATALOG_READER, DB_NAME};
18use crate::catalog::CatalogReader;
19
20/// Tests whether an index column has the named property.
21///
22/// `index` is the OID of the index.
23/// `column` is the column number (1-based) within the index.
24///
25/// NULL is returned if the property name is not known or does not apply to the particular object,
26/// or if the OID or column number does not identify a valid object.
27///
28/// # Supported Properties
29///
30/// - `asc`: Does the column sort in ascending order on a forward scan?
31/// - `desc`: Does the column sort in descending order on a forward scan?
32/// - `nulls_first`: Does the column sort with nulls first on a forward scan?
33/// - `nulls_last`: Does the column sort with nulls last on a forward scan?
34///
35/// # Examples
36///
37/// ```slt
38/// statement ok
39/// create table t(a int, b int);
40///
41/// statement ok
42/// create index i on t (a asc, b desc);
43///
44/// query B
45/// select pg_index_column_has_property('i'::regclass, 1, 'asc');
46/// ----
47/// t
48///
49/// query B
50/// select pg_index_column_has_property('i'::regclass, 1, 'DESC');
51/// ----
52/// f
53///
54/// query B
55/// select pg_index_column_has_property('i'::regclass, 1, 'nulls_FIRST');
56/// ----
57/// f
58///
59/// query B
60/// select pg_index_column_has_property('i'::regclass, 1, 'nulls_last');
61/// ----
62/// t
63///
64/// query B
65/// select pg_index_column_has_property('i'::regclass, 2, 'asc');
66/// ----
67/// f
68///
69/// query B
70/// select pg_index_column_has_property('i'::regclass, 2, 'desc');
71/// ----
72/// t
73///
74/// query B
75/// select pg_index_column_has_property('i'::regclass, 2, 'nulls_first');
76/// ----
77/// t
78///
79/// query B
80/// select pg_index_column_has_property('i'::regclass, 2, 'nulls_last');
81/// ----
82/// f
83///
84/// query B
85/// select pg_index_column_has_property('i'::regclass, 1, 'gg');    -- invalid property
86/// ----
87/// NULL
88///
89/// query B
90/// select pg_index_column_has_property('i'::regclass, 0, 'asc');   -- column 0 does not exist
91/// ----
92/// NULL
93///
94/// statement ok
95/// drop index i;
96///
97/// statement ok
98/// drop table t;
99/// ```
100#[function("pg_index_column_has_property(int4, int4, varchar) -> boolean")]
101fn pg_index_column_has_property(index: i32, column: i32, property: &str) -> Result<Option<bool>> {
102    pg_index_column_has_property_impl_captured(index, column, property)
103}
104
105#[capture_context(CATALOG_READER, DB_NAME)]
106fn pg_index_column_has_property_impl(
107    catalog: &CatalogReader,
108    db_name: &str,
109    index_id: i32,
110    column_idx: i32,
111    property: &str,
112    // `Result` is not necessary for this function, but it's required by `capture_context`.
113) -> Result<Option<bool>> {
114    let catalog_reader = catalog.read_guard();
115    let Ok(index) = catalog_reader.get_index_by_id(db_name, index_id as u32) else {
116        return Ok(None);
117    };
118    let Some(properties) = index.get_column_properties((column_idx - 1) as usize) else {
119        return Ok(None);
120    };
121    Ok(match property.to_lowercase().as_str() {
122        "asc" => Some(!properties.is_desc),
123        "desc" => Some(properties.is_desc),
124        "nulls_first" => Some(properties.nulls_first),
125        "nulls_last" => Some(!properties.nulls_first),
126        _ => None,
127    })
128}
risingwave_frontend/expr/function_impl/pg_index_column_has_property.rs

risingwave_frontend/expr/function_impl/
pg_index_column_has_property.rs
