59498caeca
Moving `function`, `function_name` and `aggregate_function` into db namespace to avoid including cql3 namespace into query-request. For now, only minimal subset of cql3 function was moved to db.
94 lines
2.4 KiB
C++
94 lines
2.4 KiB
C++
/*
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* Modified by ScyllaDB
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*
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* Copyright (C) 2022-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: (AGPL-3.0-or-later and Apache-2.0)
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*/
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#pragma once
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#include "function.hh"
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#include <optional>
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namespace db {
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namespace functions {
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/**
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* Performs a calculation on a set of values and return a single value.
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*/
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class aggregate_function : public virtual function {
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public:
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class aggregate;
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/**
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* Creates a new <code>Aggregate</code> instance.
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*
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* @return a new <code>Aggregate</code> instance.
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*/
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virtual std::unique_ptr<aggregate> new_aggregate() = 0;
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/**
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* Checks wheather the function can be distributed and is able to reduce states.
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*
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* @return <code>true</code> if the function is reducible, <code>false</code> otherwise.
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*/
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virtual bool is_reducible() const = 0;
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/**
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* Creates a <code>Aggregate Function</code> that can be reduced.
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* Such <code>Aggregate Function</code> returns <code>Aggregate</code>,
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* which returns not finalized output, but its accumulator that can be
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* later reduced with other one.
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*
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* Reducible aggregate function can be obtained only if <code>is_reducible()</code>
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* return true. Otherwise, it should return <code>nullptr</code>.
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*
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* @return a reducible <code>Aggregate Function</code>.
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*/
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virtual ::shared_ptr<aggregate_function> reducible_aggregate_function() = 0;
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/**
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* An aggregation operation.
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*/
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class aggregate {
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public:
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using opt_bytes = aggregate_function::opt_bytes;
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virtual ~aggregate() {}
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/**
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* Adds the specified input to this aggregate.
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*
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* @param protocol_version native protocol version
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* @param values the values to add to the aggregate.
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*/
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virtual void add_input(cql_serialization_format sf, const std::vector<opt_bytes>& values) = 0;
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/**
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* Computes and returns the aggregate current value.
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*
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* @param protocol_version native protocol version
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* @return the aggregate current value.
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*/
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virtual opt_bytes compute(cql_serialization_format sf) = 0;
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virtual void set_accumulator(const opt_bytes& acc) = 0;
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virtual opt_bytes get_accumulator() const = 0;
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virtual void reduce(cql_serialization_format sf, const opt_bytes& acc) = 0;
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/**
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* Reset this aggregate.
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*/
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virtual void reset() = 0;
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};
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};
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}
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}
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