m::GraphBuilder Struct Reference

#include <QueryGraph.hpp>

Inheritance diagram for m::GraphBuilder:

Collaboration diagram for m::GraphBuilder:

Public Types
using	clause_map = std::unordered_map< cnf::Clause, ClauseInfo >
	‍maps a cnf::Clause to its ClauseInfo

Public Member Functions
	GraphBuilder ()
std::unique_ptr< QueryGraph >	get ()
	‍returns the constructed QueryGraph
void	operator() (Const< ast::Stmt > &s)
void	operator() (Const< ast::ErrorStmt > &)
void	operator() (Const< ast::EmptyStmt > &)
void	operator() (Const< ast::CreateDatabaseStmt > &)
void	operator() (Const< ast::DropDatabaseStmt > &)
void	operator() (Const< ast::UseDatabaseStmt > &)
void	operator() (Const< ast::CreateTableStmt > &)
void	operator() (Const< ast::DropTableStmt > &)
void	operator() (Const< ast::SelectStmt > &s)
void	operator() (Const< ast::InsertStmt > &)
void	operator() (Const< ast::UpdateStmt > &)
void	operator() (Const< ast::DeleteStmt > &)
void	operator() (Const< ast::DSVImportStmt > &)
void	process_selection (cnf::Clause &clause)
	Computes correlation information of clause.

Private Attributes
std::vector< std::reference_wrapper< const ast::Expr > >	existing_grouping_keys_
	‍the grouping keys of the statement
std::unordered_set< std::reference_wrapper< const ast::Expr > >	additional_grouping_keys_
	‍additionally required grouping keys to perform decorrelation
clause_map	bound_clauses_
	‍to be handled by the current query
clause_map	deferred_clauses_
	‍to be handled by an outer query
std::unique_ptr< QueryGraph >	graph_
	‍the query graph that is being constructed
std::unordered_map< ThreadSafePooledString, std::reference_wrapper< DataSource > >	named_sources_
	‍maps DataSource names/aliases to the DataSource instance
bool	needs_grouping_ = false
	‍whether this graph needs grouping; either by explicily grouping or implicitly by using aggregations

Detailed Description

Definition at line 44 of file QueryGraph.hpp.

Member Typedef Documentation

clause_map

using m::GraphBuilder::clause_map = std::unordered_map<cnf::Clause, ClauseInfo>

‍maps a cnf::Clause to its ClauseInfo

Definition at line 47 of file QueryGraph.hpp.

Constructor & Destructor Documentation

GraphBuilder()

GraphBuilder::GraphBuilder

(

)

Definition at line 410 of file QueryGraph.cpp.

Member Function Documentation

get()

std::unique_ptr< QueryGraph > m::GraphBuilder::get ( )

inline

‍returns the constructed QueryGraph

Definition at line 72 of file QueryGraph.hpp.

References graph_.

Referenced by m::QueryGraph::Build().

operator()() [1/13]

void m::GraphBuilder::operator() ( Const< ast::CreateDatabaseStmt > &  )

inline

Definition at line 79 of file QueryGraph.hpp.

References M_unreachable.

operator()() [2/13]

void m::GraphBuilder::operator() ( Const< ast::CreateTableStmt > &  )

inline

Definition at line 82 of file QueryGraph.hpp.

References M_unreachable.

operator()() [3/13]

void m::GraphBuilder::operator() ( Const< ast::DeleteStmt > &  )

inline

Definition at line 87 of file QueryGraph.hpp.

References M_unreachable.

operator()() [4/13]

void m::GraphBuilder::operator() ( Const< ast::DropDatabaseStmt > &  )

inline

Definition at line 80 of file QueryGraph.hpp.

References M_unreachable.

operator()() [5/13]

void m::GraphBuilder::operator() ( Const< ast::DropTableStmt > &  )

inline

Definition at line 83 of file QueryGraph.hpp.

References M_unreachable.

operator()() [6/13]

void m::GraphBuilder::operator() ( Const< ast::DSVImportStmt > &  )

inline

Definition at line 88 of file QueryGraph.hpp.

References M_unreachable.

operator()() [7/13]

void m::GraphBuilder::operator() ( Const< ast::EmptyStmt > &  )

inline

Definition at line 78 of file QueryGraph.hpp.

operator()() [8/13]

void m::GraphBuilder::operator() ( Const< ast::ErrorStmt > &  )

inline

Definition at line 77 of file QueryGraph.hpp.

References M_unreachable.

operator()() [9/13]

void m::GraphBuilder::operator() ( Const< ast::InsertStmt > &  )

inline

Definition at line 85 of file QueryGraph.hpp.

References M_unreachable.

operator()() [10/13]

void m::GraphBuilder::operator()

(

Const< ast::SelectStmt > &

s

)

operator()() [11/13]

void m::GraphBuilder::operator() ( Const< ast::Stmt > &  s )

inline

Definition at line 76 of file QueryGraph.hpp.

operator()() [12/13]

void m::GraphBuilder::operator() ( Const< ast::UpdateStmt > &  )

inline

Definition at line 86 of file QueryGraph.hpp.

References M_unreachable.

operator()() [13/13]

void m::GraphBuilder::operator() ( Const< ast::UseDatabaseStmt > &  )

inline

Definition at line 81 of file QueryGraph.hpp.

References M_unreachable.

process_selection()

void GraphBuilder::process_selection

(

cnf::Clause &

clause

)

Computes correlation information of clause.

Analyzes the entire clause for how it can be decorrelated.

1. If the query does not have any grouping, clauses can be trivially decorrelated by lifting the clause into the join condition of the dependent join.

If the query contains grouping, more in depth analysis is performed:

1. If the clause contains only bound variables, it is an uncorrelated selection of the query.
2. If the clause contains only free variables, it is an uncorrelated selection of an outer statement.
3. If it contains both bound and free variables, it is correlated and is analyzed more closely. Correlated clauses can be decorrelated if all bound expressions are composable of the grouping keys specified in the query. If it is not possible to compose all bound expressions from grouping keys, the clause cannot be decorrelated.
4. A special exception are clauses of a single equi-predicate, where one side of the equi-predicate contains only bound variables and the other contains only free variables. In that particular case, we can decorrelate the clause by introducing the bound expression as an additional grouping key to the query.

Definition at line 440 of file QueryGraph.cpp.

References additional_grouping_keys_, m::and, m::ClauseInfo::binding_depth, bound_clauses_, deferred_clauses_, existing_grouping_keys_, graph_, is_composable_of(), M_insist, named_sources_, needs_grouping_, and m::ClauseInfo::nested_queries.

Field Documentation

additional_grouping_keys_

std::unordered_set<std::reference_wrapper<const ast::Expr> > m::GraphBuilder::additional_grouping_keys_

private

‍additionally required grouping keys to perform decorrelation

Definition at line 54 of file QueryGraph.hpp.

Referenced by process_selection().

bound_clauses_

clause_map m::GraphBuilder::bound_clauses_

private

‍to be handled by the current query

Definition at line 57 of file QueryGraph.hpp.

Referenced by process_selection().

deferred_clauses_

clause_map m::GraphBuilder::deferred_clauses_

private

‍to be handled by an outer query

Definition at line 59 of file QueryGraph.hpp.

Referenced by process_selection().

existing_grouping_keys_

std::vector<std::reference_wrapper<const ast::Expr> > m::GraphBuilder::existing_grouping_keys_

private

‍the grouping keys of the statement

Definition at line 52 of file QueryGraph.hpp.

Referenced by process_selection().

graph_

std::unique_ptr<QueryGraph> m::GraphBuilder::graph_

private

‍the query graph that is being constructed

Definition at line 62 of file QueryGraph.hpp.

Referenced by get(), and process_selection().

named_sources_

std::unordered_map<ThreadSafePooledString, std::reference_wrapper<DataSource> > m::GraphBuilder::named_sources_

private

‍maps DataSource names/aliases to the DataSource instance

Definition at line 64 of file QueryGraph.hpp.

Referenced by process_selection().

needs_grouping_

bool m::GraphBuilder::needs_grouping_ = false

private

‍whether this graph needs grouping; either by explicily grouping or implicitly by using aggregations

Definition at line 66 of file QueryGraph.hpp.

Referenced by process_selection().

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The documentation for this struct was generated from the following files:

• src/IR/QueryGraph.hpp
• src/IR/QueryGraph.cpp