ClickHouse/src/Core/Joins.h
2023-12-18 15:02:51 +00:00

123 lines
4.2 KiB
C++

#pragma once
#include <string_view>
namespace DB
{
/// Join method.
enum class JoinKind
{
Inner, /// Leave only rows that was JOINed.
Left, /// If in "right" table there is no corresponding rows, use default values instead.
Right,
Full,
Cross, /// Direct product. Strictness and condition doesn't matter.
Comma, /// Same as direct product. Intended to be converted to INNER JOIN with conditions from WHERE.
Paste, /// Used to join parts without `ON` clause.
};
const char * toString(JoinKind kind);
inline constexpr bool isLeft(JoinKind kind) { return kind == JoinKind::Left; }
inline constexpr bool isRight(JoinKind kind) { return kind == JoinKind::Right; }
inline constexpr bool isInner(JoinKind kind) { return kind == JoinKind::Inner; }
inline constexpr bool isFull(JoinKind kind) { return kind == JoinKind::Full; }
inline constexpr bool isCrossOrComma(JoinKind kind) { return kind == JoinKind::Comma || kind == JoinKind::Cross; }
inline constexpr bool isRightOrFull(JoinKind kind) { return kind == JoinKind::Right || kind == JoinKind::Full; }
inline constexpr bool isLeftOrFull(JoinKind kind) { return kind == JoinKind::Left || kind == JoinKind::Full; }
inline constexpr bool isInnerOrRight(JoinKind kind) { return kind == JoinKind::Inner || kind == JoinKind::Right; }
inline constexpr bool isInnerOrLeft(JoinKind kind) { return kind == JoinKind::Inner || kind == JoinKind::Left; }
inline constexpr bool isPaste(JoinKind kind) { return kind == JoinKind::Paste; }
/// Allows more optimal JOIN for typical cases.
enum class JoinStrictness
{
Unspecified,
RightAny, /// Old ANY JOIN. If there are many suitable rows in right table, use any from them to join.
Any, /// Semi Join with any value from filtering table. For LEFT JOIN with Any and RightAny are the same.
All, /// If there are many suitable rows to join, use all of them and replicate rows of "left" table (usual semantic of JOIN).
Asof, /// For the last JOIN column, pick the latest value
Semi, /// LEFT or RIGHT. SEMI LEFT JOIN filters left table by values exists in right table. SEMI RIGHT - otherwise.
Anti, /// LEFT or RIGHT. Same as SEMI JOIN but filter values that are NOT exists in other table.
};
const char * toString(JoinStrictness strictness);
/// Algorithm for distributed query processing.
enum class JoinLocality
{
Unspecified,
Local, /// Perform JOIN, using only data available on same servers (co-located data).
Global /// Collect and merge data from remote servers, and broadcast it to each server.
};
const char * toString(JoinLocality locality);
/// ASOF JOIN inequality type
enum class ASOFJoinInequality
{
None,
Less,
Greater,
LessOrEquals,
GreaterOrEquals,
};
const char * toString(ASOFJoinInequality asof_join_inequality);
inline constexpr ASOFJoinInequality getASOFJoinInequality(std::string_view func_name)
{
ASOFJoinInequality inequality = ASOFJoinInequality::None;
if (func_name == "less")
inequality = ASOFJoinInequality::Less;
else if (func_name == "greater")
inequality = ASOFJoinInequality::Greater;
else if (func_name == "lessOrEquals")
inequality = ASOFJoinInequality::LessOrEquals;
else if (func_name == "greaterOrEquals")
inequality = ASOFJoinInequality::GreaterOrEquals;
return inequality;
}
inline constexpr ASOFJoinInequality reverseASOFJoinInequality(ASOFJoinInequality inequality)
{
if (inequality == ASOFJoinInequality::Less)
return ASOFJoinInequality::Greater;
else if (inequality == ASOFJoinInequality::Greater)
return ASOFJoinInequality::Less;
else if (inequality == ASOFJoinInequality::LessOrEquals)
return ASOFJoinInequality::GreaterOrEquals;
else if (inequality == ASOFJoinInequality::GreaterOrEquals)
return ASOFJoinInequality::LessOrEquals;
return ASOFJoinInequality::None;
}
enum class JoinAlgorithm
{
DEFAULT = 0,
AUTO,
HASH,
PARTIAL_MERGE,
PREFER_PARTIAL_MERGE,
PARALLEL_HASH,
GRACE_HASH,
DIRECT,
FULL_SORTING_MERGE,
};
const char * toString(JoinAlgorithm join_algorithm);
enum class JoinTableSide
{
Left,
Right
};
const char * toString(JoinTableSide join_table_side);
}