PlanExecState is an abstract interface for execution state of various query plan. More...

#include <execution/PlanExecState.h>

Inheritance diagram for taco::PlanExecState:

Public Member Functions
template<class ... UniquePtrs>
	PlanExecState (NodeTag tag, UniquePtrs &&...input)
	Base constructor for all execution states. More...

virtual	~PlanExecState ()
	Deconstructor of PlanExecState. More...

virtual void	init ()=0
	Initialize this plan execution state, set `m_initialized` to true and initialize all corresponding states (including its children) to get ready for query processing. More...

virtual bool	next_tuple ()=0
	Moves the iterator of this execution state to the next output record. More...

virtual std::vector< NullableDatumRef >	get_record ()=0
	Return the deserialized output record to which this execution state currently points. More...

virtual void	close ()=0
	Clear internal states, mark we have finish retrieving output records from this execution state, and mark the execution state no longer initialzied. More...

virtual Datum	save_position () const
	Returns a saved position where this plan execution state is at. More...

virtual void	rewind ()=0
	Rewind the execution state as if it has just been initialized. More...

virtual bool	rewind (DatumRef saved_position)
	Rewinds the execution state to the same as the one that was previously saved and returns if the rewinded state is currently at a valid record. More...

virtual const PlanNode *	get_plan () const =0
	Returns the corresponding plan. More...

Public Member Functions inherited from taco::TreeNode
template<class ... UniquePtrs>
	TreeNode (NodeTag tag, UniquePtrs &&...input)

virtual	~TreeNode ()

	TreeNode (TreeNode &&)=default

TreeNode &	operator= (TreeNode &&)=default

	TreeNode (const TreeNode &)=delete

TreeNode &	operator= (const TreeNode &)=delete

constexpr NodeTag	get_tag () const

TreeNode *	get_input (size_t i) const

template<class Node >
Node *	get_input_as (size_t i) const

std::string	to_string () const

void	node_to_string (std::string &buf, int indent) const
	Prints the node contents to a string buffer. More...

const char *	node_name () const

virtual void	node_properties_to_string (std::string &buf, int indent) const =0

Protected Member Functions
PlanExecState *	get_child (size_t i) const
	Utility function to get the raw pointer of `i-th` child of this execution state. More...

Protected Attributes
bool	m_initialized

Additional Inherited Members
Static Public Member Functions inherited from taco::TreeNode
static void	append_indent (std::string &buf, int indent)

Detailed Description

PlanExecState is an abstract interface for execution state of various query plan.

Each execution state should correspond to a query plan. It operates like as an iterator iterating through the records produced by a plan for a specific query instance.

Constructor & Destructor Documentation

◆ PlanExecState()

template<class ... UniquePtrs>

taco::PlanExecState::PlanExecState	(	NodeTag	tag,
		UniquePtrs &&...	input
	)

inline

Base constructor for all execution states.

It is marked with a node tag (see include/utils/tree/node_Tags.inc for more details) and unique pointers to all of its children execution states. When just constructed, the execution states are NOT initialized until init() is called.

The unique pointers to its children will be moved to TreeNode internal states after the construction so you don't have to remember it separately.

Note: You can use TAG(ClassName) to get the corresponding tag for a plan execution state. For example, TAG(SelectionState) will give you the tag of SelectionState.

◆ ~PlanExecState()

virtual taco::PlanExecState::~PlanExecState ( )

inlinevirtual

Deconstructor of PlanExecState.

When it is destroyed, you have to make sure this execution state is no longer initialized. Otherwise, its behavior is undefined.

Member Function Documentation

◆ close()

virtual void taco::PlanExecState::close ( )

pure virtual

Clear internal states, mark we have finish retrieving output records from this execution state, and mark the execution state no longer initialzied.

A closed operator may be reopened by calling init() again.

Implemented in taco::TempTableState, taco::TableScanState, taco::TableInsertState, taco::TableDeleteState, taco::SortState, taco::SelectionState, taco::ProjectionState, taco::LimitState, taco::IndexScanState, taco::CartesianProductState, and taco::AggregationState.

◆ get_child()

PlanExecState* taco::PlanExecState::get_child ( size_t i ) const

inlineprotected

Utility function to get the raw pointer of i-th child of this execution state.

◆ get_plan()

virtual const PlanNode* taco::PlanExecState::get_plan ( ) const

pure virtual

Returns the corresponding plan.

Implemented in taco::TempTableState, taco::TableScanState, taco::TableInsertState, taco::TableDeleteState, taco::SortState, taco::SelectionState, taco::ProjectionState, taco::LimitState, taco::IndexScanState, taco::CartesianProductState, and taco::AggregationState.

◆ get_record()

virtual std::vector<NullableDatumRef> taco::PlanExecState::get_record ( )

pure virtual

Return the deserialized output record to which this execution state currently points.

The deserialized record represented by a vector of NullableDatumRef should be SAFE to access until the next_tuple() is called again on the same execution state.

It should return the first output record after the first next_tuple call. The behavior of calling get_record() before the first next_tuple() is undefined.

Implemented in taco::TempTableState, taco::TableScanState, taco::TableInsertState, taco::TableDeleteState, taco::SortState, taco::SelectionState, taco::ProjectionState, taco::LimitState, taco::IndexScanState, taco::CartesianProductState, and taco::AggregationState.

◆ init()

virtual void taco::PlanExecState::init ( )

pure virtual

Initialize this plan execution state, set m_initialized to true and initialize all corresponding states (including its children) to get ready for query processing.

Implemented in taco::TempTableState, taco::TableScanState, taco::TableInsertState, taco::TableDeleteState, taco::SortState, taco::SelectionState, taco::ProjectionState, taco::LimitState, taco::IndexScanState, taco::CartesianProductState, and taco::AggregationState.

◆ next_tuple()

virtual bool taco::PlanExecState::next_tuple ( )

pure virtual

Moves the iterator of this execution state to the next output record.

Returns true if there is such a record. The caller should be able to get the current deserialized record through get_record() before another next_tuple() is called or the plan execution state is implicitly or explicitly ended. You should make sure memory holding this record is safe (on pinned page or copied somewhere) until the next next_tuple() call.

Implemented in taco::TempTableState, taco::TableScanState, taco::TableInsertState, taco::TableDeleteState, taco::SortState, taco::SelectionState, taco::ProjectionState, taco::LimitState, taco::IndexScanState, taco::CartesianProductState, and taco::AggregationState.

◆ rewind() [1/2]

virtual void taco::PlanExecState::rewind ( )

pure virtual

Rewind the execution state as if it has just been initialized.

Thus, after this call, next_tuple() will trigger another round of scan from the very beginning. Calling rewind() should have the same effect as calling close() followed by another init(), but is usually a more efficient because it may avoid certain memory deallocation/allocation or recomputation.

Note that an operator must support this overload of rewind() even if it does not support rewinding to a saved position.

Implemented in taco::TempTableState, taco::TableScanState, taco::TableInsertState, taco::TableDeleteState, taco::SortState, taco::SelectionState, taco::ProjectionState, taco::LimitState, taco::IndexScanState, taco::CartesianProductState, and taco::AggregationState.

◆ rewind() [2/2]

virtual bool taco::PlanExecState::rewind ( DatumRef saved_position )

inlinevirtual

Rewinds the execution state to the same as the one that was previously saved and returns if the rewinded state is currently at a valid record.

Calling get_record() on the rewinded object will return the same values for the same record at the time the the saved_position was returned by save_position().

It is undefined if this function is passed a saved_position that was not returned by this plan execution state object.

Reimplemented in taco::TempTableState, taco::TableScanState, taco::SortState, taco::SelectionState, taco::ProjectionState, taco::LimitState, taco::IndexScanState, taco::CartesianProductState, and taco::AggregationState.

◆ save_position()

virtual Datum taco::PlanExecState::save_position ( ) const

inlinevirtual

Returns a saved position where this plan execution state is at.

A call to rewind(DatumRef) with the saved position will rewind the execution state to the same as its current state. Calling get_record() on the rewinded object will return the same values for the same record at the time the save_position() is called. The returned saved position must not be null.

An operator that does not support rewinding to a saved position should never override this function.

Reimplemented in taco::TempTableState, taco::TableScanState, taco::SortState, taco::SelectionState, taco::ProjectionState, taco::LimitState, taco::IndexScanState, taco::CartesianProductState, and taco::AggregationState.

Member Data Documentation

◆ m_initialized

bool taco::PlanExecState::m_initialized

protected

The documentation for this class was generated from the following file:

execution/PlanExecState.h

Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ PlanExecState()

◆ ~PlanExecState()

Member Function Documentation

◆ close()

◆ get_child()

◆ get_plan()

◆ get_record()

◆ init()

◆ next_tuple()

◆ rewind() [1/2]

◆ rewind() [2/2]

◆ save_position()

Member Data Documentation

◆ m_initialized