datafusion_functions_aggregate_common/
accumulator.rs

1// Licensed to the Apache Software Foundation (ASF) under one
2// or more contributor license agreements.  See the NOTICE file
3// distributed with this work for additional information
4// regarding copyright ownership.  The ASF licenses this file
5// to you under the Apache License, Version 2.0 (the
6// "License"); you may not use this file except in compliance
7// with the License.  You may obtain a copy of the License at
8//
9//   http://www.apache.org/licenses/LICENSE-2.0
10//
11// Unless required by applicable law or agreed to in writing,
12// software distributed under the License is distributed on an
13// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14// KIND, either express or implied.  See the License for the
15// specific language governing permissions and limitations
16// under the License.
17
18use arrow::datatypes::{DataType, FieldRef, Schema};
19use datafusion_common::Result;
20use datafusion_expr_common::accumulator::Accumulator;
21use datafusion_physical_expr_common::physical_expr::PhysicalExpr;
22use datafusion_physical_expr_common::sort_expr::PhysicalSortExpr;
23use std::sync::Arc;
24
25/// [`AccumulatorArgs`] contains information about how an aggregate
26/// function was called, including the types of its arguments and any optional
27/// ordering expressions.
28#[derive(Debug, Clone)]
29pub struct AccumulatorArgs<'a> {
30    /// The return field of the aggregate function.
31    pub return_field: FieldRef,
32
33    /// Input schema to the aggregate function. If you need to check data type, nullability
34    /// or metadata of input arguments then you should use `expr_fields` below instead.
35    pub schema: &'a Schema,
36
37    /// Whether to ignore nulls.
38    ///
39    /// SQL allows the user to specify `IGNORE NULLS`, for example:
40    ///
41    /// ```sql
42    /// SELECT FIRST_VALUE(column1) IGNORE NULLS FROM t;
43    /// ```
44    pub ignore_nulls: bool,
45
46    /// The expressions in the `ORDER BY` clause passed to this aggregator.
47    ///
48    /// SQL allows the user to specify the ordering of arguments to the
49    /// aggregate using an `ORDER BY`. For example:
50    ///
51    /// ```sql
52    /// SELECT FIRST_VALUE(column1 ORDER BY column2) FROM t;
53    /// ```
54    pub order_bys: &'a [PhysicalSortExpr],
55
56    /// Whether the aggregation is running in reverse order
57    pub is_reversed: bool,
58
59    /// The name of the aggregate expression
60    pub name: &'a str,
61
62    /// Whether the aggregate function is distinct.
63    ///
64    /// ```sql
65    /// SELECT COUNT(DISTINCT column1) FROM t;
66    /// ```
67    pub is_distinct: bool,
68
69    /// The physical expression of arguments the aggregate function takes.
70    pub exprs: &'a [Arc<dyn PhysicalExpr>],
71
72    /// Fields corresponding to each expr (same order & length).
73    pub expr_fields: &'a [FieldRef],
74}
75
76impl AccumulatorArgs<'_> {
77    /// Returns the return type of the aggregate function.
78    pub fn return_type(&self) -> &DataType {
79        self.return_field.data_type()
80    }
81}
82
83/// Factory that returns an accumulator for the given aggregate function.
84pub type AccumulatorFactoryFunction =
85    Arc<dyn Fn(AccumulatorArgs) -> Result<Box<dyn Accumulator>> + Send + Sync>;
86
87/// [`StateFieldsArgs`] contains information about the fields that an
88/// aggregate function's accumulator should have. Used for `AggregateUDFImpl::state_fields`.
89pub struct StateFieldsArgs<'a> {
90    /// The name of the aggregate function.
91    pub name: &'a str,
92
93    /// The input fields of the aggregate function.
94    pub input_fields: &'a [FieldRef],
95
96    /// The return fields of the aggregate function.
97    pub return_field: FieldRef,
98
99    /// The ordering fields of the aggregate function.
100    pub ordering_fields: &'a [FieldRef],
101
102    /// Whether the aggregate function is distinct.
103    pub is_distinct: bool,
104}
105
106impl StateFieldsArgs<'_> {
107    /// The return type of the aggregate function.
108    pub fn return_type(&self) -> &DataType {
109        self.return_field.data_type()
110    }
111}
datafusion_functions_aggregate_common/accumulator.rs

datafusion_functions_aggregate_common/
accumulator.rs
