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
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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
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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, Field, 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::LexOrdering;
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)]
29pub struct AccumulatorArgs<'a> {
30    /// The return type of the aggregate function.
31    pub return_type: &'a DataType,
32
33    /// The schema of the input arguments
34    pub schema: &'a Schema,
35
36    /// Whether to ignore nulls.
37    ///
38    /// SQL allows the user to specify `IGNORE NULLS`, for example:
39    ///
40    /// ```sql
41    /// SELECT FIRST_VALUE(column1) IGNORE NULLS FROM t;
42    /// ```
43    pub ignore_nulls: bool,
44
45    /// The expressions in the `ORDER BY` clause passed to this aggregator.
46    ///
47    /// SQL allows the user to specify the ordering of arguments to the
48    /// aggregate using an `ORDER BY`. For example:
49    ///
50    /// ```sql
51    /// SELECT FIRST_VALUE(column1 ORDER BY column2) FROM t;
52    /// ```
53    ///
54    /// If no `ORDER BY` is specified, `ordering_req` will be empty.
55    pub ordering_req: &'a LexOrdering,
56
57    /// Whether the aggregation is running in reverse order
58    pub is_reversed: bool,
59
60    /// The name of the aggregate expression
61    pub name: &'a str,
62
63    /// Whether the aggregate function is distinct.
64    ///
65    /// ```sql
66    /// SELECT COUNT(DISTINCT column1) FROM t;
67    /// ```
68    pub is_distinct: bool,
69
70    /// The physical expression of arguments the aggregate function takes.
71    pub exprs: &'a [Arc<dyn PhysicalExpr>],
72}
73
74/// Factory that returns an accumulator for the given aggregate function.
75pub type AccumulatorFactoryFunction =
76    Arc<dyn Fn(AccumulatorArgs) -> Result<Box<dyn Accumulator>> + Send + Sync>;
77
78/// [`StateFieldsArgs`] contains information about the fields that an
79/// aggregate function's accumulator should have. Used for `AggregateUDFImpl::state_fields`.
80pub struct StateFieldsArgs<'a> {
81    /// The name of the aggregate function.
82    pub name: &'a str,
83
84    /// The input types of the aggregate function.
85    pub input_types: &'a [DataType],
86
87    /// The return type of the aggregate function.
88    pub return_type: &'a DataType,
89
90    /// The ordering fields of the aggregate function.
91    pub ordering_fields: &'a [Field],
92
93    /// Whether the aggregate function is distinct.
94    pub is_distinct: bool,
95}
datafusion_functions_aggregate_common/accumulator.rs

datafusion_functions_aggregate_common/
accumulator.rs
