IndexScanState is the execution state for index based table scan. More...

#include <execution/IndexScanState.h>

Inheritance diagram for taco::IndexScanState:

Public Member Functions
	~IndexScanState () override

void	node_properties_to_string (std::string &buf, int indent) const override

void	init () override
	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...

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

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

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

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

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

bool	rewind (DatumRef saved_position) override
	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...

const PlanNode *	get_plan () const override
	Returns the corresponding plan. More...

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

virtual	~PlanExecState ()
	Deconstructor of PlanExecState. 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

Private Member Functions
	IndexScanState (const IndexScan *plan, std::unique_ptr< Index > idx)

Private Attributes
const IndexScan *	m_plan

Friends
class	IndexScan

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

Protected Member Functions inherited from taco::PlanExecState
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 inherited from taco::PlanExecState
bool	m_initialized

Detailed Description

IndexScanState is the execution state for index based table scan.

This execution state should return all heap file records statisfying the range its physical plan indicates. Note that you should return heap file records rather than RecordID.

An index access interface Index is passed as idx when constructed. All index accesses to the underlying index should go through that access interface.

CAUTION: You need to make sure the output record's NullableDatumRef are always memory safe at any time until the operator is closed.

Constructor & Destructor Documentation

◆ ~IndexScanState()

taco::IndexScanState::~IndexScanState ( )

override

◆ IndexScanState()

taco::IndexScanState::IndexScanState	(	const IndexScan *	plan,
		std::unique_ptr< Index >	idx
	)

private

Member Function Documentation

◆ close()

void taco::IndexScanState::close ( )

overridevirtual

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.

Implements taco::PlanExecState.

◆ get_plan()

const PlanNode* taco::IndexScanState::get_plan ( ) const

inlineoverridevirtual

Returns the corresponding plan.

Implements taco::PlanExecState.

◆ get_record()

std::vector< NullableDatumRef > taco::IndexScanState::get_record ( )

overridevirtual

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.

Implements taco::PlanExecState.

◆ init()

void taco::IndexScanState::init ( )

overridevirtual

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

Implements taco::PlanExecState.

◆ next_tuple()

bool taco::IndexScanState::next_tuple ( )

overridevirtual

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.

Implements taco::PlanExecState.

◆ node_properties_to_string()

void taco::IndexScanState::node_properties_to_string	(	std::string &	buf,
		int	indent
	)		const

overridevirtual

Implements taco::TreeNode.

◆ rewind() [1/2]

void taco::IndexScanState::rewind ( )

overridevirtual

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.

Implements taco::PlanExecState.

◆ rewind() [2/2]

bool taco::IndexScanState::rewind ( DatumRef saved_position )

overridevirtual

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 from taco::PlanExecState.

◆ save_position()

Datum taco::IndexScanState::save_position ( ) const

overridevirtual

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 from taco::PlanExecState.

Friends And Related Function Documentation

◆ IndexScan

friend class IndexScan

friend

Member Data Documentation

◆ m_plan

const IndexScan* taco::IndexScanState::m_plan

private

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

execution/IndexScanState.h
execution/IndexScanState.cpp

Public Member Functions

Private Member Functions

Private Attributes

Friends

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ ~IndexScanState()

◆ IndexScanState()

Member Function Documentation

◆ close()

◆ get_plan()

◆ get_record()

◆ init()

◆ next_tuple()

◆ node_properties_to_string()

◆ rewind() [1/2]

◆ rewind() [2/2]

◆ save_position()

Friends And Related Function Documentation

◆ IndexScan

Member Data Documentation

◆ m_plan