mirror of
https://github.com/scylladb/scylladb.git
synced 2026-04-26 03:20:37 +00:00
42a1ced73b
The expression system uses managed_bytes_opt for values, but result_set uses bytes_opt. This means that processing values from the result set in expressions requires a copy. Out of the two, managed_bytes_opt is the better choice, since it prevents large contiguous allocations for large blobs. So we switch result_set to use managed_bytes_opt. Users of the result_set API are adjusted. The db::function interface is not modified to limit churn; instead we convert the types on entry and exit. This will be adjusted in a following patch.
106 lines
2.5 KiB
C++
106 lines
2.5 KiB
C++
/*
|
|
* Copyright (C) 2015-present ScyllaDB
|
|
*
|
|
* Modified by ScyllaDB
|
|
*/
|
|
|
|
/*
|
|
* SPDX-License-Identifier: (AGPL-3.0-or-later and Apache-2.0)
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include "cql3/selection/selection.hh"
|
|
#include "cql3/selection/selector.hh"
|
|
|
|
namespace cql3 {
|
|
|
|
namespace selection {
|
|
|
|
class simple_selector_factory : public selector::factory {
|
|
private:
|
|
const sstring _column_name;
|
|
const uint32_t _idx;
|
|
data_type _type;
|
|
public:
|
|
simple_selector_factory(const sstring& column_name, uint32_t idx, data_type type)
|
|
: _column_name(std::move(column_name))
|
|
, _idx(idx)
|
|
, _type(type)
|
|
{ }
|
|
|
|
virtual bool is_simple_selector_factory() const override {
|
|
return true;
|
|
}
|
|
|
|
virtual sstring column_name() const override {
|
|
return _column_name;
|
|
}
|
|
|
|
virtual data_type get_return_type() const override {
|
|
return _type;
|
|
}
|
|
|
|
virtual ::shared_ptr<selector> new_instance() const override;
|
|
};
|
|
|
|
class simple_selector : public selector {
|
|
private:
|
|
const sstring _column_name;
|
|
const uint32_t _idx;
|
|
data_type _type;
|
|
managed_bytes_opt _current;
|
|
bool _first; ///< Whether the next row we receive is the first in its group.
|
|
public:
|
|
static ::shared_ptr<factory> new_factory(const sstring& column_name, uint32_t idx, data_type type) {
|
|
return ::make_shared<simple_selector_factory>(column_name, idx, type);
|
|
}
|
|
|
|
simple_selector(const sstring& column_name, uint32_t idx, data_type type)
|
|
: _column_name(std::move(column_name))
|
|
, _idx(idx)
|
|
, _type(type)
|
|
, _first(true)
|
|
{ }
|
|
|
|
virtual void add_input(result_set_builder& rs) override {
|
|
// GROUP BY calls add_input() repeatedly without reset() in between, and it expects the
|
|
// output to be the first value encountered:
|
|
// https://cassandra.apache.org/doc/latest/cql/dml.html#grouping-results
|
|
if (_first) {
|
|
// TODO: can we steal it?
|
|
_current = (*rs.current)[_idx];
|
|
_first = false;
|
|
}
|
|
}
|
|
|
|
virtual managed_bytes_opt get_output() override {
|
|
return std::move(_current);
|
|
}
|
|
|
|
virtual void reset() override {
|
|
_current = {};
|
|
_first = true;
|
|
}
|
|
|
|
virtual data_type get_type() const override {
|
|
return _type;
|
|
}
|
|
|
|
virtual sstring assignment_testable_source_context() const override {
|
|
return _column_name;
|
|
}
|
|
|
|
#if 0
|
|
@Override
|
|
public String toString()
|
|
{
|
|
return columnName;
|
|
}
|
|
#endif
|
|
};
|
|
|
|
}
|
|
|
|
}
|