778ae2b461
Temporaries are similar to bind variables - they are values provided from outside the expression. While bind variables are provided by the user, temporaries are generated internally. The intended use is for aggregate accumulator storage. Currently aggregates store the accumulator in aggregate_function_selector::_accumulator, which means the entire selector hierarchy must be cloned for every query. With expressions, we can have a single expression object reused for many computations, but we need a way to inject the accumulator into an aggregation, which this new expression element provides.
41 lines
1.2 KiB
C++
41 lines
1.2 KiB
C++
// Copyright (C) 2023-present ScyllaDB
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// SPDX-License-Identifier: AGPL-3.0-or-later
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#pragma once
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#include "expression.hh"
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#include "bytes.hh"
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#include <vector>
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namespace cql3 {
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class query_options;
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class raw_value;
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}
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namespace cql3::expr {
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// Input data needed to evaluate an expression. Individual members can be
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// null if not applicable (e.g. evaluating outside a row context)
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struct evaluation_inputs {
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std::span<const bytes> partition_key;
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std::span<const bytes> clustering_key;
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std::span<const managed_bytes_opt> static_and_regular_columns; // indexes match `selection` member
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const cql3::selection::selection* selection = nullptr;
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const query_options* options = nullptr;
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std::span<const api::timestamp_type> static_and_regular_timestamps; // indexes match `selection` member
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std::span<const int32_t> static_and_regular_ttls; // indexes match `selection` member
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std::span<const cql3::raw_value> temporaries; // indexes match temporary::index
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};
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// Takes a prepared expression and calculates its value.
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// Evaluates bound values, calls functions and returns just the bytes and type.
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cql3::raw_value evaluate(const expression& e, const evaluation_inputs&);
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cql3::raw_value evaluate(const expression& e, const query_options&);
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}
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